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                                 FORM 10-Q


                    SECURITIES AND EXCHANGE COMMISSION
                         WASHINGTON, D. C.  20549

(Mark One)

(X)  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2004

                                    OR

( )  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934

For the transition period from _________________ to _______________

Commission file number 0-19601

          SOUTWEST ROYALTIES INSTITUTIONAL 1990-91 INCOME PROGRAM
          Southwest Royalties Institutional Income Fund X-B, L.P.
                  (Exact name of registrant as specified
                   in its limited partnership agreement)

Delaware                                          75-2332174
(State or other jurisdiction of                                  (I.R.S.
Employer
incorporation or organization)
          Identification No.)

                               6 Desta Drive
                           Midland, Texas 79705
                 (Address of principal executive offices)

                               432-682-6324
                      (Registrant's telephone number,
                           including area code)

Indicate  by  check  mark  whether registrant (1)  has  filed  all  reports
required to be filed by Section 13 or 15(d) of the Securities Exchange  Act
of 1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject  to
such filing requirements for the past 90 days:
                              Yes X No ___

Indicate  by check mark whether the registrant is an accelerated filer  (as
defined in Exchange Act Rule 12b-2).     Yes     No  X

The  registrant's  outstanding  securities  consist  of  Units  of  limited
partnership  interests for which there exists no established public  market
from which to base a calculation of aggregate market value.


         The total number of pages contained in this report is 23.


Glossary of Oil and Gas Terms
The  following are abbreviations and definitions of terms commonly used  in
the  oil  and  gas industry that are used in this filing.  All  volumes  of
natural gas referred to herein are stated at the legal pressure base to the
state  or area where the reserves exit and at 60 degrees Fahrenheit and  in
most instances are rounded to the nearest major multiple.

     Bbl. One stock tank barrel, or 42 United States gallons liquid volume.

     Developmental well. A well drilled within the proved area of an oil or
natural gas reservoir to the depth of a stratigraphic horizon known  to  be
productive.

     Exploratory well. A well drilled to find and produce oil or gas in  an
unproved  area to find a new reservoir in a field previously  found  to  be
productive of oil or natural gas in another reservoir or to extend a  known
reservoir.

     Farm-out  arrangement. An agreement whereby the owner of the leasehold
or  working  interest  agrees to assign his interest  in  certain  specific
acreage  to  the assignee, retaining some interest, such as  an  overriding
royalty interest, subject to the drilling of one (1) or more wells or other
performance by the assignee.

     Field. An area consisting of a single reservoir or multiple reservoirs
all  grouped  on  or  related to the same individual geological  structural
feature and/or stratigraphic condition.

     Mcf. One thousand cubic feet.

     Net  Profits  Interest.  An agreement whereby  the  owner  receives  a
specified  percentage of the defined net profits from a producing  property
in  exchange for consideration paid.  The net profits interest  owner  will
not otherwise participate in additional costs and expenses of the property.

     Oil. Crude oil, condensate and natural gas liquids.

     Overriding  royalty  interest. Interests that  are  carved  out  of  a
working  interest, and their duration is limited by the term of  the  lease
under which they are created.

     Present  value  and  PV-10 Value. When used with respect  to  oil  and
natural gas reserves, the estimated future net revenue to be generated from
the  production of proved reserves, determined in all material respects  in
accordance  with  the  rules and regulations of the  SEC  (generally  using
prices  and costs in effect as of the date indicated) without giving effect
to  non-property  related  expenses  such  as  general  and  administrative
expenses,  debt service and future income tax expenses or to  depreciation,
depletion  and  amortization, discounted using an annual discount  rate  of
10%.

     Production  costs.  Costs incurred to operate and maintain  wells  and
related  equipment  and facilities, including depreciation  and  applicable
operating  costs  of support equipment and facilities and  other  costs  of
operating and maintaining those wells and related equipment and facilities.

     Proved Area. The part of a property to which proved reserves have been
specifically attributed.

     Proved  developed oil and gas reserves. Proved developed oil  and  gas
reserves  are  reserves that can be expected to be recovered from  existing
wells with existing equipment and operating methods.

     Proved properties. Properties with proved reserves.

     Proved  reserves. The estimated quantities of crude oil, natural  gas,
and  natural  gas liquids that geological and engineering data  demonstrate
with  reasonable  certainty to be recoverable in future  years  from  known
reservoirs under existing economic and operating conditions.

     Proved  undeveloped reserves. Proved undeveloped oil and gas  reserves
are  reserves that are expected to be recovered from new wells on undrilled
acreage,  or  from existing wells where a relatively major  expenditure  is
required for recompletion.

     Reservoir.  A porous and permeable underground formation containing  a
natural  accumulation  of  producible  oil  or  gas  that  is  confined  by
impermeable  rock  or water barriers and is individual  and  separate  from
other reservoirs.

     Royalty  interest.  An  interest in an oil and  natural  gas  property
entitling  the  owner to a share of oil or natural gas production  free  of
costs of production.

     Working  interest.  The operating interest that gives  the  owner  the
right  to  drill, produce and conduct operating activities on the  property
and a share of production.

     Workover.  Operations  on  a producing well  to  restore  or  increase
production.



                      PART I. - FINANCIAL INFORMATION

Item 1.  Financial Statements

The  unaudited  condensed financial statements included  herein  have  been
prepared  by  the Registrant (herein also referred to as the "Partnership")
in  accordance  with generally accepted accounting principles  for  interim
financial information and with the instructions to Form 10-Q and Rule 10-01
of Regulation S-X.  Accordingly, they do not include all of the information
and  footnotes  required  by generally accepted accounting  principles  for
complete   financial  statements.   In  the  opinion  of  management,   all
adjustments necessary for a fair presentation have been included and are of
a  normal  recurring nature.  The financial statements should  be  read  in
conjunction with the audited financial statements and the notes thereto for
the  year ended December 31, 2003, which are found in the Registrant's Form
10-K  Report  for  2003 filed with the Securities and Exchange  Commission.
The December 31, 2003 balance sheet included herein has been taken from the
Registrant's  2003 Form 10-K Report.  Operating results for the  three  and
nine-month  periods ended September 30, 2004 are not necessarily indicative
of the results that may be expected for the full year.


          Southwest Royalties Institutional Income Fund X-B, L.P.
                              Balance Sheets

                                 Septembe  December
                                  r 30,      31,
                                   2004      2003
                                  -----     -----
                                 (unaudit
                                   ed)
Assets
- ---------

Current assets:
 Cash and cash equivalents    $  94,882    11,800
  Receivable  from  Managing     130,104   50,094
General Partner
                                 --------  --------
                                 ----      -----
   Total current assets          224,986   61,894
                                 --------  --------
                                 ----      -----
Oil  and  gas  properties  -
using the full-
 cost method of accounting       3,933,60  3,934,20
                                 9         3
       Less      accumulated
depreciation,
         depletion       and     3,611,41  3,596,25
amortization                     1         7
                                 --------  --------
                                 ----      -----
      Net   oil   and    gas     322,198   337,946
properties
                                 --------  --------
                                 ----      -----
                              $  547,184   399,840
                                 =======   =======

Liabilities  and   Partners'
Equity
- ----------------------------
- ----

Current     liability      -  $  -         332
distribution payable
                                 --------  --------
                                 ----      -----

Asset retirement obligation      217,633   205,889
                                 --------  --------
                                 ----      -----
Partners' equity:
 General partner                 (43,240)  (60,160)
 Limited partners                372,791   253,779
                                 --------  --------
                                 ----      -----
   Total partners' equity        329,551   193,619
                                 --------  --------
                                 ----      -----
                              $  547,184   399,840
                                 =======   =======


          Southwest Royalties Institutional Income Fund X-B, L.P.
                         Statements of Operations
                                (unaudited)

                                    Three Months Ended   Nine Months Ended
                                      September 30,        September 30,
                                     2004       2003      2004      2003
                                     -----     -----      -----     -----
Revenues
- ------------
Income from net profits          $ 159,626   29,906     399,197   209,809
interests
Interest                           149       57         254       322
Other                              -         -          250       117
                                   --------  ---------  --------  --------
                                   --                   --        -
                                   159,775   29,963     399,701   210,248
                                   --------  ---------  --------  --------
                                   --                   --        -
Expenses
- ------------
General and administrative         22,429    21,523     68,166    67,688
Depreciation, depletion and        5,154     6,000      15,154    18,000
amortization
Accretion of asset retirement      4,107     3,811      12,339    11,522
obligation
                                   --------  ---------  --------  --------
                                   --                   --        -
                                   31,690    31,334     95,659    97,210
                                   --------  ---------  --------  --------
                                   --                   --        -
Net income (loss) before           128,085   (1,371)    304,042   113,038
cumulative effects

Cumulative effect of change in
accounting
  principle - SFAS No. 143 -       -         -          -         (91,424)
See Note 3
                                   --------  ---------  --------  --------
                                   --                   --        -
Net income (loss)                $ 128,085   (1,371)    304,042   21,614
                                   ======    =====      ======    =====
Net income (loss) allocated to:

  Managing General Partner       $ 11,992    417        28,728    3,565
                                   ======    =====      ======    =====
  General Partner                $ 1,332     46         3,192     396
                                   ======    =====      =====     =====
  Limited Partners               $ 114,761   (1,834)    272,122   17,653
                                   ======    =====      ======    =====
     Per limited partner unit    $  10.26     (.16)      24.34
before cumulative effect                                          8.94
     Cumulative effects per        -         -          -          (7.36)
limited partner unit
                                   --------  ---------  --------  --------
                                   --                   --        -
     Per limited partner unit    $  10.26     (.16)      24.34
                                                                  1.58
                                   ======    =====      ======    =====

          Southwest Royalties Institutional Income Fund X-B, L.P.
                         Statements of Cash Flows
                                (unaudited)

                                                     Nine Months Ended
                                                       September 30,
                                                       2004     2003
                                                      -----     -----
            Cash flows from operating activities

            Cash received from income from net
              profits interests                    $ 307,642  198,044
            Cash paid to suppliers                   (56,622  (51,774)
                                                     )
            Interest received                        254      322
            Other                                    250      117
                                                     -------  --------
                                                     ---      --
              Net cash provided by operating         251,524  146,709
            activities
                                                     -------  --------
                                                     ---      --
            Cash flows used in financing
            activities

            Distributions to partners                (168,44  (169,668
                                                     2)       )
                                                     -------  --------
                                                     ---      --
              Net increase (decrease) in cash        83,082   (22,959)
            and cash equivalents

            Beginning of period                      11,800   64,725
                                                     -------  --------
                                                     ---      --
            End of period                          $ 94,882   41,766
                                                     ======   ======
            Reconciliation of net income to net
            cash
            provided by operating activities

            Net income                             $ 304,042  21,614

            Adjustments to reconcile net income
            to net
            cash provided by operating
            activities

            Depreciation, depletion and              15,154   18,000
            amortization
            Accretion of asset retirement            12,339   11,522
            obligation
            Cumulative effect of change in
            accounting
              principle - SFAS No. 143               -        91,424
            Increase in receivables                  (91,555  (11,765)
                                                     )
            Increase in payables                     11,544   15,914
                                                     -------  --------
                                                     ---      --
            Net cash provided by operating         $ 251,524  146,709
            activities
                                                     ======   ======
            Noncash investing and financing
            activities:

            Increase in oil and gas properties -
            Adoption
              of SFAS No. 143                      $ -        101,341
                                                     ======   ======
            Increase in oil and gas properties -
            SFAS No. 143
              Add new wells                        $ 57       -
                                                     ======   ======
            Decrease in oil and gas properties -
            SFAS No. 143
              Asset retirement obligation          $ -        2,287
            settlement
                                                     ======   ======
            Decrease in oil and gas properties -
            SFAS No. 143
              Plug and abandoned wells             $ 651      -
                                                     ======   ======
         Southwest Royalties Institutional Income Fund X-B, L.P.
                     (a Delaware limited partnership)

                      Notes to Financial Statements

1.   Organization
     Southwest  Royalties Institutional Income Fund X-B, L.P. was organized
     under  the laws of the state of Delaware on November 27, 1990 for  the
     purpose  of acquiring producing oil and gas properties and to  produce
     and market crude oil and natural gas produced from such properties for
     a  term  of 50 years, unless terminated at an earlier date as provided
     for  in the Partnership Agreement.  The Partnership sells its oil  and
     gas  production to a variety of purchasers with the prices it receives
     being  dependent  upon the oil and gas economy.  Southwest  Royalties,
     Inc.  a  wholly  owned  subsidiary of Clayton Williams  Energy,  Inc.,
     serves as the Managing General Partner and Blue Heel Company, a wholly
     owned  subsidiary of Southwest Royalties, Inc., acquired  the  general
     partner interest from H.H. Wommack, III.  Revenues, costs and expenses
     are allocated as follows:

                         Limited   General
                         Partners  Partners
                         --------  --------
Interest   income    on  100%      -
capital contributions
Oil and gas sales        90%       10%
All other revenues       90%       10%
Organization        and  100%      -
offering costs (1)
Amortization         of  100%      -
organization costs
Property    acquisition  100%      -
costs
Gain/loss  on  property  90%       10%
disposition
Operating           and  90%       10%
administrative    costs
(2)
Depreciation, depletion
and amortization
   of   oil   and   gas  100%      -
properties
All other costs          90%       10%

          (1)All  organization  costs in excess of 3%  of  initial  capital
          contributions  will be paid by the Managing General  Partner  and
          will  be treated as a capital contribution.  The Partnership paid
          the  Managing  General Partner an amount equal to 3%  of  initial
          capital contributions for such organization costs.

          (2)Administrative costs in any year, which exceed 2%  of  capital
          contributions shall be paid by the Managing General  Partner  and
          will be treated as a capital contribution.

2.   Summary of Significant Accounting Policies
     The  interim financial information as of September 30, 2004,  and  for
     the  three  and  nine months ended September 30, 2004,  is  unaudited.
     Certain  information  and footnote disclosures  normally  included  in
     financial  statements prepared in accordance with  generally  accepted
     accounting principles have been condensed or omitted in this Form 10-Q
     pursuant  to the rules and regulations of the Securities and  Exchange
     Commission.  However,  in  the opinion of  management,  these  interim
     financial  statements include all the necessary adjustments to  fairly
     present  the  results of the interim periods and all such  adjustments
     are  of a normal recurring nature.  The interim consolidated financial
     statements should be read in conjunction with the Partnership's Annual
     Report on Form 10-K for the year ended December 31, 2003.

3.   Cumulative effect of change in accounting principle - SFAS No. 143
     On  January  1, 2003, the Partnership adopted Statement  of  Financial
     Accounting   Standards  No.  143,  Accounting  for  Asset   Retirement
     Obligations  ("SFAS No. 143").  Adoption of SFAS No. 143  is  required
     for  all  companies with fiscal years beginning after June  15,  2002.
     The new standard requires the Partnership to recognize a liability for
     the  present  value  of  all  legal obligations  associated  with  the
     retirement  of tangible long-lived assets and to capitalize  an  equal
     amount as a cost of the asset and depreciate the additional cost  over
     the  estimated  useful  life of the asset.  On January  1,  2003,  the
     Partnership    recorded   additional   costs,   net   of   accumulated
     depreciation,  of  approximately $101,341, a long  term  liability  of
     approximately  $192,765 and a loss of approximately  $91,424  for  the
     cumulative  effect  on  depreciation  of  the  additional  costs   and
     accretion  expense  on  the liability related to expected  abandonment
     costs  of  its oil and natural gas producing properties.  At September
     30,  2004,  the  asset  retirement obligation was  $217,633,  and  the
     increase  in  the  balance from January 1, 2004 is  due  to  accretion
     expense  of  $12,339 and the addition of new wells  of  $57  partially
     offset by a reduction for plug and abandoned wells of $651.

          Southwest Royalties Institutional Income Fund X-B, L.P.
                     (a Delaware limited partnership)

                      Notes to Financial Statements

4.   Change in Control of Managing General Partner
     On  May  21,  2004,  Clayton Williams Energy, Inc.  acquired  all  the
     outstanding common stock of Southwest Royalties Inc. through a merger.
     Clayton  Williams  Energy,  Inc. paid  $57.1  million  to  holders  of
     Southwest  Royalties,  Inc.  common stock and  common  stock  warrants
     ($45.01   per   share)   and  assumed  and  refinanced   approximately
     $113.9  million  of assumed bank debt at closing.  In connection  with
     the  transaction,  Blue  Heel Company, a wholly  owned  subsidiary  of
     Southwest Royalties, Inc., acquired the general partner interest  from
     H.H. Wommack, III.


Item 2. Management's Discussion and Analysis of Financial Condition and
Results of Operations

General
Southwest Royalties Institutional Income Fund X-B, L.P. was organized as  a
Delaware  limited  partnership on November 27, 1990. The offering  of  such
limited  partnership interests began December 1, 1990 as part  of  a  shelf
offering registered under the name Southwest Royalties Institutional  1990-
91  Income Program.  Minimum capital requirements for the Partnership  were
met  on  March 11, 1991, with the offering of limited partnership interests
concluding September 30, 1991, with total limited partner contributions  of
$5,590,500.

The Partnership was formed to acquire royalty and net profits interests  in
producing  oil  and  gas properties, to produce and market  crude  oil  and
natural  gas  produced  from such properties, and  to  distribute  the  net
proceeds from operations to the limited and general partners.  Net revenues
from  producing  oil  and gas properties will not be  reinvested  in  other
revenue  producing  assets except to the extent that production  facilities
and wells are improved or reworked or where methods are employed to improve
or  enable  more efficient recovery of oil and gas reserves.  The  economic
life  of  the  Partnership  thus  depends on  the  period  over  which  the
Partnership's oil and gas reserves are economically recoverable

Increases   or   decreases   in  Partnership   revenues   and,   therefore,
distributions  to partners will depend primarily on changes in  the  prices
received  for  production,  changes in volumes of  production  sold,  lease
operating  expenses, enhanced recovery projects, offset drilling activities
pursuant to farmout arrangements, sales of properties, and the depletion of
wells.  Since wells deplete over time, production can generally be expected
to decline from year to year.

Well  operating costs and general and administrative costs usually decrease
with   production   declines;  however,  these  costs  may   not   decrease
proportionately.  Net income available for distribution to the partners  is
therefore expected to fluctuate in later years based on these factors.

Oil and Gas Properties
Oil  and  gas  properties  are accounted for at cost  under  the  full-cost
method.  Under this method, all productive and nonproductive costs incurred
in  connection with the acquisition, exploration and development of oil and
gas  reserves  are capitalized.  Gain or loss on the sale of  oil  and  gas
properties  is not recognized unless significant oil and gas  reserves  are
sold.

Should the net capitalized costs exceed the estimated present value of  oil
and gas reserves, discounted at 10%, such excess costs would be charged  to
current  expense.  As of September 30, 2004, the net capitalized costs  did
not exceed the estimated present value of oil and gas reserves.

The  Partnership's  interest  in oil and gas  properties  consists  of  net
profits  interests  in  proved properties located  within  the  continental
United  States.   A net profits interest is created when  the  owner  of  a
working  interest in a property enters into an arrangement  providing  that
the  net profits interest owner will receive a stated percentage of the net
profit  from  the  property.   The  net profits  interest  owner  will  not
otherwise participate in additional costs and expenses of the property.

The  Partnership recognizes income from its net profits interest in oil and
gas property on an accrual basis, while the quarterly cash distributions of
the net profits interest are based on a calculation of actual cash received
from  oil  and  gas sales, net of expenses incurred during  that  quarterly
period.   If  the  net  profits interest calculation  results  in  expenses
incurred  exceeding the oil and gas income received during  a  quarter,  no
cash  distribution is due to the Partnership's net profits  interest  until
the  deficit is recovered from future net profits.  The Partnership accrues
a quarterly loss on its net profits interest provided there is a cumulative
net  amount  due for accrued revenue as of the balance sheet date.   As  of
September 30, 2004, there were no timing differences, which resulted  in  a
deficit net profit interest.

Critical Accounting Policies

The  Partnership follows the full cost method of accounting for its oil and
gas  properties.   The  full cost method subjects  companies  to  quarterly
calculations of a "ceiling", or limitation on the amount of properties that
can  be capitalized on the balance sheet.  If the Partnership's capitalized
costs  are in excess of the calculated ceiling, the excess must be  written
off as an expense.

The  Partnership's discounted present value of its proved oil  and  natural
gas  reserves  is  a  major  component  of  the  ceiling  calculation,  and
represents  the  component  that requires the  most  subjective  judgments.
Estimates  of  reserves are forecasts based on engineering data,  projected
future  rates  of  production and the timing of future  expenditures.   The
process  of  estimating oil and natural gas reserves  requires  substantial
judgment,  resulting  in  imprecise determinations,  particularly  for  new
discoveries.   Different reserve engineers may make different estimates  of
reserve  quantities  based  on the same data.   The  Partnership's  reserve
estimates are prepared by outside consultants.  Quarterly reserve estimates
are prepared by the Managing General Partner's internal staff of engineers.

The  passage  of  time  provides  more  qualitative  information  regarding
estimates of reserves, and revisions are made to prior estimates to reflect
updated  information.   However,  there  can  be  no  assurance  that  more
significant  revisions  will not be necessary in  the  future.   If  future
significant  revisions  are  necessary  that  reduce  previously  estimated
reserve quantities, it could result in a full cost property writedown.   In
addition to the impact of these estimates of proved reserves on calculation
of  the  ceiling,  estimates  of proved reserves  are  also  a  significant
component of the calculation of DD&A.

While  the quantities of proved reserves require substantial judgment,  the
associated prices of oil and natural gas reserves that are included in  the
discounted  present  value of the reserves do not  require  judgment.   The
ceiling calculation dictates that prices and costs in effect as of the last
day  of  the  period are generally held constant indefinitely. Because  the
ceiling  calculation dictates that prices in effect as of the last  day  of
the  applicable quarter are held constant indefinitely, the resulting value
is  not indicative of the true fair value of the reserves.  Oil and natural
gas  prices have historically been cyclical and, on any particular  day  at
the  end of a quarter, can be either substantially higher or lower than the
Partnership's  long-term price forecast that is a barometer for  true  fair
value.

Results of Operations

A.  General Comparison of the Quarters Ended September 30, 2004 and 2003

The  following  table  provides certain information  regarding  performance
factors for the quarters ended September 30, 2004 and 2003:

                                    Three Months
                                       Ended         Percenta
                                                        ge
                                   September 30,     Increase
                                   2004      2003    (Decreas
                                                        e)
                                  -----     -----    --------
                                                        --
Average price per barrel  of  $   42.21              45%
oil                                        29.17
Average price per mcf of gas  $    5.15              25%
                                           4.11
Oil production in barrels        4,520     4,650     (3%)
Gas production in mcf            17,979    16,500    9%
Income   from  net   profits  $  159,626   29,906    434%
interests
Partnership distributions     $  100,000   -         100%
Limited              partner  $  90,000    -         100%
distributions
Per  unit  distribution   to
limited
 partners                     $    8.05         -    100%
Number  of  limited  partner     11,181    11,181
units

Revenues

The  Partnership's income from net profits interests increased to  $159,626
from   $29,906  for  the  quarters  ended  September  30,  2004  and  2003,
respectively,  an  increase of 434%.  The principal factors  affecting  the
comparison  of  the  quarters ended September 30,  2004  and  2003  are  as
follows:

1.   The  average  price  for a barrel of oil received by  the  Partnership
     increased  during the quarter ended September 30, 2004 as compared  to
     the  quarter  ended September 30, 2003 by 45%, or $13.04  per  barrel,
     resulting in an increase of approximately $58,900 in income  from  net
     profits  interests.  Oil sales represented 67% of total  oil  and  gas
     sales  during the quarter ended September 30, 2004 as compared to  67%
     during the quarter ended September 30, 2002.

     The  average  price  for  an mcf of gas received  by  the  Partnership
     increased  during the same period by 25%, or $1.04 per mcf,  resulting
     in  an  increase of approximately $18,700 in income from  net  profits
     interests.

     The  total  increase in income from net profits interests due  to  the
     change in prices received from oil and gas production is approximately
     $77,600.  The market price for oil and gas has been extremely volatile
     over  the  past  decade, and management expects a  certain  amount  of
     volatility to continue in the foreseeable future.


2. Oil  production  decreased approximately 130 barrels or  3%  during  the
   quarter  ended  September  30, 2004 as compared  to  the  quarter  ended
   September  30, 2003, resulting in a decrease of approximately $3,800  in
   income from net profits interests.

    Gas  production increased approximately 1,479 mcf or 9% during the same
    period, resulting in an increase of approximately $6,100 in income from
    net profits interests.

    The net increase in income from net profits interests due to the change
    in production is approximately $2,300.

3.  Lease  operating  costs  and  production  taxes  were  29%  lower,   or
    approximately $49,800 less during the quarter ended September 30,  2004
    as  compared to the quarter ended September 30, 2003.  Lease  operating
    costs in 2003 included well workover costs on one well.

Costs and Expenses

Total costs and expenses increased to $31,690 from $31,334 for the quarters
ended  September 30, 2004 and 2003, respectively, an increase of  1%.   The
increase  is  a  result  of  higher  accretion  expense  and  general   and
administrative  expense,  partially  offset  by  a  decrease  in  depletion
expense.

1.  General and administrative costs consists of independent accounting and
    engineering  fees,  computer services, postage,  and  Managing  General
    Partner personnel costs.  General and administrative costs increased 4%
    or  approximately $900 during the quarter ended September 30,  2004  as
    compared to the quarter ended September 30, 2003.

2.  Depletion  expense decreased to $5,154 for the quarter ended  September
    30,  2004  from $6,000 for the same period in 2003.  This represents  a
    decrease  of 14%.  The contributing factor to the decrease in depletion
    expense is in relation to the BOE depletion rate for the quarter  ended
    September 30, 2004, which was $.69 applied to 7,517 BOE as compared  to
    $.81  applied  to  7,400 BOE for the same period in  2003.   The  lower
    depreciation  rate  in 2004 is due to the upward  revision  in  reserve
    estimates resulting from higher oil and gas prices.

3.  Accretion  expense increased to $4,107 for the quarter ended  September
    30,  2004 from $3,811 for the same period in 2003.  This represents  an
    increase of 8%.



B.   General Comparison of the Nine-Month Periods Ended September 30,  2004
and 2003

The  following  table  provides certain information  regarding  performance
factors for the nine-month periods ended September 30, 2004 and 2003:

                               Nine Months
                                  Ended         Percenta
                                                   ge
                              September 30,     Increase
                              2004      2003    (Decreas
                                                   e)
                             -----     -----    --------
                                                   --
Average    price    per  $   37.36              23%
barrel of oil                         30.36
Average  price per  mcf  $    5.30              11%
of gas                                4.76
Oil    production    in     13,820    14,550    (5%)
barrels
Gas production in mcf       48,459    47,900    1%
Income from net profits  $  399,197   209,809   90%
interests
Partnership              $  168,110   170,000   (1%)
distributions
Limited         partner  $  153,110   153,000   -
distributions
Per  unit  distribution
to limited
 partners                $   13.69              -
                                      13.68
Number    of    limited     11,181    11,181
partner units

Revenues

The  Partnership's income from net profits interests increased to  $399,197
from  $209,809  for  the nine months ended September  30,  2004  and  2003,
respectively,  an  increase of 90%.  The principal  factors  affecting  the
comparison  of  the nine months ended September 30, 2004 and  2003  are  as
follows:

1.  The  average  price  for a barrel of oil received  by  the  Partnership
    increased  during the nine months ended September 30, 2004 as  compared
    to  the  nine  months ended September 30, 2003 by  23%,  or  $7.00  per
    barrel,  resulting  in an increase of approximately $96,700  in  income
    from net profits interests.  Oil sales represented 67% of total oil and
    gas  sales  during  the nine months ended September 30,  2004  and  66%
    during the nine months ended September 30, 2003.

    The  average  price  for  an  mcf of gas received  by  the  Partnership
    increased during the same period by 11%, or $.54 per mcf, resulting  in
    an  increase  of  approximately $26,200  in  income  from  net  profits
    interests.

    The  total  increase in income from net profits interests  due  to  the
    change  in prices received from oil and gas production is approximately
    $122,900.  The market price for oil and gas has been extremely volatile
    over  the  past  decade, and management expects  a  certain  amount  of
    volatility to continue in the foreseeable future.


2.  Oil  production decreased approximately 730 barrels or  5%  during  the
    nine  months  ended September 30, 2004 as compared to the  nine  months
    ended  September  30,  2003, resulting in a decrease  of  approximately
    $22,200 in income from net profits interests.

    Gas  production increased approximately 559 mcf or 1% during  the  same
    period, resulting in an increase of approximately $2,700 in income from
    net profits interests.

    The  net total decrease in income from net profits interests due to the
    change in production is approximately $19,500.

3.    Lease  operating  costs  and production  taxes  were  19%  lower,  or
   approximately $85,700 less during the nine months ended September 30, 2004
   as compared to the nine months ended September 30, 2003.  Lease operating
   costs in 2003 included well workover costs on three wells.

Costs and Expenses

Total  costs  and expenses decreased to $95,659 from $97,210 for  the  nine
months  ended September 30, 2004 and 2003, respectively, a decrease of  2%.
The decrease is a result of lower depletion expense, partially offset by an
increase in general and administrative expense and accretion expense.

1.    General  and administrative costs consists of independent  accounting
   and  engineering fees, computer services, postage, and Managing  General
   Partner personnel costs.  General and administrative costs increased 1% or
   approximately $500 during the nine months ended September  30,  2004  as
   compared to the nine months ended September 30, 2003.

2.  Depletion  expense  decreased to $15,154  for  the  nine  months  ended
    September  30,  2004 from $18,000 for the same period  in  2003.   This
    represents a decrease of 16%.  The contributing factor to the  decrease
    in  depletion expense is in relation to the BOE depletion rate for  the
    nine  months ended September 30, 2004, which was $.69 applied to 21,897
    BOE  as  compared to $.80 applied to 22,533 BOE for the same period  in
    2003.   The  lower  depreciation rate in 2004  is  due  to  the  upward
    revision in reserve estimates resulting from higher oil and gas prices.

3.  Accretion  expense  increased to $12,339  for  the  nine  months  ended
    September  30,  2004 from $11,522 for the same period  in  2003.   This
    represents an increase of 7%.



Liquidity and Capital Resources

The  primary source of cash is from operations, the receipt of income  from
interests in oil and gas properties.  The Partnership knows of no  material
change, nor does it anticipate any such change.

Cash flows provided by operating activities were approximately $251,500  in
the  nine  months  ended  September 30, 2004 as compared  to  approximately
$146,700 in the nine months ended September 30, 2003.

Cash flows used in financing activities were approximately $168,400 in  the
nine  months ended September 30, 2004 as compared to approximately $169,700
in  the  nine  months ended September 30, 2003.  The only use in  financing
activities was the distributions to partners.

Total  distributions during the nine months ended September 30,  2004  were
$168,110  of  which  $153,110 was distributed to the limited  partners  and
$15,000  to  the  general partners.  The per unit distribution  to  limited
partners during the nine months ended September 30, 2004 was $13.69.  Total
distributions during the nine months ended September 30, 2003 were $170,000
of  which  $153,000 was distributed to the limited partners and $17,000  to
the general partners.  The per unit distribution to limited partners during
the nine months ended September 30, 2003 was $13.68.

The  source  for  the  2004  distributions of $168,110  were  oil  and  gas
operations  of  approximately  $251,500,  resulting  in  excess  cash   for
contingencies  or  subsequent  distributions.  The  source  for  the   2003
distributions  of  $170,000  were oil and gas operations  of  approximately
$146,700, with the balance from available cash on hand at the beginning  of
the period.

Cumulative cash distributions of $6,013,599 have been made to the partners.
As  of  September 30, 2004, $5,473,093 or $489.50 per limited partner  unit
has been distributed to the limited partners, representing a 98% return  of
the capital contributed.

As  of  September 30, 2004, the Partnership had approximately  $225,000  in
working  capital.   The  Managing  General  Partner  knows  of  no  unusual
contractual  commitments.  The partnership held many long-lived  properties
at  inception,  however  due to the restrictions  on  property  development
imposed  by  the partnership agreement, the Partnership cannot develop  its
non-producing  properties.   Without continued development,  the  producing
reserves continue to deplete.  Accordingly, as the Partnership's properties
have  matured  and  depleted, the net cash flows from  operations  for  the
partnership  has  steadily  declined, except in  periods  of  substantially
increased  commodity pricing.  Maintenance of properties and administrative
expenses for the Partnership are increasing relative to production.  As the
properties   continue   to   deplete,   maintenance   of   properties   and
administrative costs as a percentage of production are expected to continue
to increase.

Managing General Partner

On May 21, 2004, Clayton Williams Energy, Inc. acquired all the outstanding
common  stock  of  Southwest  Royalties Inc.  through  a  merger.   Clayton
Williams Energy, Inc. paid $57.1 million to holders of Southwest Royalties,
Inc.  common stock and common stock warrants ($45.01 per share) and assumed
and  refinanced  approximately  $113.9 million  of  assumed  bank  debt  at
closing.   In connection with the transaction, Blue Heel Company, a  wholly
owned subsidiary of Southwest Royalties, Inc., acquired the general partner
interest from H.H. Wommack, III.



Item 3.   Quantitative and Qualitative Disclosures About Market Risk

The  Partnership  is  not a party to any derivative or embedded  derivative
instruments.

Disclosure Controls and Procedures
As  of  the nine months ended September 30, 2004, L. Paul Latham, President
and  Chief  Executive Officer of the Managing General Partner, and  Mel  G.
Riggs,  Vice President and Chief Financial Officer of the Managing  General
Partner,  evaluated  the  effectiveness  of  the  Partnership's  disclosure
controls and procedures.  Based on their evaluation, they believe that:

     The  disclosure  controls  and  procedures  of  the  Partnership  were
     effective in ensuring that information required to be disclosed by the
     Partnership in the reports it files or submits under the Exchange  Act
     was  recorded,  processed,  summarized and reported  within  the  time
     periods specified in the SEC's rules and forms; and

     The  disclosure  controls  and  procedures  of  the  Partnership  were
     effective  in  ensuring  that  material  information  required  to  be
     disclosed by the Partnership in the report it filed or submitted under
     the  Exchange  Act was accumulated and communicated  to  the  Managing
     General  Partner's  management, including its Chief Executive  Officer
     and  Chief Financial Officer, as appropriate to allow timely decisions
     regarding required disclosure.

Internal Control Over Financial Reporting
There  has  not been any change in the Partnership's internal control  over
financial  reporting that occurred during the nine months  ended  September
30,  2004  that  has  materially  affected,  or  is  reasonably  likely  to
materially affect, internal control over financial reporting.



                        PART II - OTHER INFORMATION


Item 1.  Legal Proceedings

         None

Item 2.  Changes in Securities

         None

Item 3.  Defaults Upon Senior Securities

         None

Item 4.  Submission of Matter to a Vote of Security Holders

         None

Item 5.  Other Information

         None

Item 6.  Exhibits and Reports on Form 8-K

          (a)  Exhibits:

               31.1 Rule 13a-14(a)/15d-14(a) Certification
31.2 Rule 13a-14(a)/15d-14(a) Certification
               32.1 Certification of Chief Executive Officer Pursuant to
18 U.S.C. Section
                  1350, as
                  adopted  Pursuant  to Section 906 of  the  Sarbanes-Oxley
                  Act of 2002
               32.2 Certification of Chief Financial Officer Pursuant to
 18 U.S.C. Section
                  1350, as
                  adopted  Pursuant  to Section 906 of  the  Sarbanes-Oxley
                  Act of 2002

             (a)  No reports on Form 8-K were filed during the quarter for
             which this report is filed.





                                SIGNATURES


Pursuant  to the requirements of the Securities Exchange Act of  1934,  the
registrant  has duly caused this report to be signed on its behalf  by  the
undersigned thereunto duly authorized.

                                 SOUTHWEST ROYALTIES INSTITUTIONAL
                                 INCOME FUND X-B, L.P.
                                 a Delaware limited partnership


                                 By:   Southwest Royalties, Inc.
                                       Managing General Partner


                                 By: /s/ Mel G. Riggs
                                   Mel G. Riggs
                                     Vice  President  and  Chief  Financial
Officer


Date:  November 15, 2004


                    SECTION 302 CERTIFICATION                Exhibit 31.1


I, L. Paul Latham, certify that:

1.   I  have  reviewed  this quarterly report on  Form  10-Q  of  Southwest
Royalties Institutional Income Fund X-B, L.P.

2.Based  on my knowledge, this report does not contain any untrue statement
  of  a  material fact or omit to state a material fact necessary  to  make
  the  statements  made,  in light of the circumstances  under  which  such
  statements  were made, not misleading with respect to the period  covered
  by this report;

3.Based  on  my  knowledge, the financial statements, and  other  financial
  information  included  in  this report, fairly present  in  all  material
  respects  the financial condition, results of operations and  cash  flows
  of the registrant as of, and for, the periods presented in this report;

4.The  registrant's other certifying officer(s) and I are  responsible  for
  establishing  and  maintaining disclosure  controls  and  procedures  (as
  defined   in  Exchange  Act  Rules  13a-15(e)  and  15d-15(e))  for   the
  registrant and have:

  a)Designed  such  disclosure  controls and  procedures,  or  caused  such
     disclosure   controls  and  procedures  to  be  designed   under   our
     supervision,  to  ensure  that material information  relating  to  the
     registrant, including its consolidated subsidiaries, is made known  to
     us  by others within those entities, particularly during the period in
     which this report is being prepared;

  b)Evaluated  the  effectiveness of the registrant's  disclosure  controls
     and  procedures and presented in this report our conclusions about the
     effectiveness of the disclosure controls and procedures, as of the end
     of the period covered by this report based on such evaluation; and

  c)Disclosed  in  this  report  any change in  the  registrant's  internal
     control over financial reporting that occurred during the registrant's
     most recent fiscal quarter (the registrant's fourth fiscal quarter  in
     the  case  of  an annual report) that has materially affected,  or  is
     reasonably  likely  to  materially affect, the  registrant's  internal
     control over financial reporting; and

5.The  registrant's other certifying officer(s) and I have disclosed, based
  on  our  most  recent  evaluation  of  internal  control  over  financial
  reporting,  to  the  registrant's auditors and  the  audit  committee  of
  registrant's  board  of directors (or persons performing  the  equivalent
  functions):

  a)All  significant deficiencies and material weaknesses in the design  or
     operation   of   internal  control  over  financial  reporting   which
     reasonably  likely  to  adversely affect the registrant's  ability  to
     record, process, summarize and report financial information; and

  b)Any  fraud, whether or not material, that involves management or  other
     employees  who  have  a significant role in the registrant's  internal
     control over financial reporting.


Date:  November 15, 2004           /s/ L. Paul Latham
                                   L. Paul Latham
                                   President and Chief Executive Officer
                                   of Southwest Royalties, Inc., the
                                   Managing General Partner of
                                   Southwest Royalties Institutional Income
Fund X-B, L.P.



                    SECTION 302 CERTIFICATION                Exhibit 31.2


I, Mel G. Riggs, certify that:

1.   I  have  reviewed  this quarterly report on  Form  10-Q  of  Southwest
Royalties Institutional Income Fund X-B, L.P.

2.Based  on my knowledge, this report does not contain any untrue statement
  of  a  material fact or omit to state a material fact necessary  to  make
  the  statements  made,  in light of the circumstances  under  which  such
  statements  were made, not misleading with respect to the period  covered
  by this report;

3.Based  on  my  knowledge, the financial statements, and  other  financial
  information  included  in  this report, fairly present  in  all  material
  respects  the financial condition, results of operations and  cash  flows
  of the registrant as of, and for, the periods presented in this report;

4.The  registrant's other certifying officer(s) and I are  responsible  for
  establishing  and  maintaining disclosure  controls  and  procedures  (as
  defined   in  Exchange  Act  Rules  13a-15(e)  and  15d-15(e))  for   the
  registrant and have:

  a)Designed  such  disclosure  controls and  procedures,  or  caused  such
     disclosure   controls  and  procedures  to  be  designed   under   our
     supervision,  to  ensure  that material information  relating  to  the
     registrant, including its consolidated subsidiaries, is made known  to
     us  by others within those entities, particularly during the period in
     which this report is being prepared;

  b)Evaluated  the  effectiveness of the registrant's  disclosure  controls
     and  procedures and presented in this report our conclusions about the
     effectiveness of the disclosure controls and procedures, as of the end
     of the period covered by this report based on such evaluation; and

  c)Disclosed  in  this  report  any change in  the  registrant's  internal
     control over financial reporting that occurred during the registrant's
     most recent fiscal quarter (the registrant's fourth fiscal quarter  in
     the  case  of  an annual report) that has materially affected,  or  is
     reasonably  likely  to  materially affect, the  registrant's  internal
     control over financial reporting; and

5.The  registrant's other certifying officer(s) and I have disclosed, based
  on  our  most  recent  evaluation  of  internal  control  over  financial
  reporting,  to  the  registrant's auditors and  the  audit  committee  of
  registrant's  board  of directors (or persons performing  the  equivalent
  functions):

  a)All  significant deficiencies and material weaknesses in the design  or
     operation   of   internal  control  over  financial  reporting   which
     reasonably  likely  to  adversely affect the registrant's  ability  to
     record, process, summarize and report financial information; and

  b)Any  fraud, whether or not material, that involves management or  other
     employees  who  have  a significant role in the registrant's  internal
     control over financial reporting.


Date:  November 15, 2004           /s/ Mel G. Riggs
                                   Mel G. Riggs
                                     Vice  President  and  Chief  Financial
Officer of
                                   Southwest Royalties, Inc., the
                                   Managing General Partner of
                                   Southwest Royalties Institutional Income
Fund X-B, L.P.




                    CERTIFICATION PURSUANT TO              Exhibit
                                   32.1
                          19 U.S.C. SECTION 1350,
                          AS ADOPTED PURSUANT TO
               SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


      In  connection  with  the  Quarterly Report  of  Southwest  Royalties
Institutional Income Fund X-B, L. P. (the "Company") on Form 10-Q  for  the
period  ending September 30, 2004 as filed with the Securities and Exchange
Commission  on  the  date hereof (the "Report"), I, L. Paul  Latham,  Chief
Executive Officer of the Managing General Partner of the Company,  certify,
pursuant  to 18 U.S.C.  1350, as adopted pursuant to  906 of the  Sarbanes-
Oxley Act of 2002, that:

     (1)  The Report fully complies with the requirements of section 13(a) or
       15(d) of the Securities Exchange Act of 1934; and

     (2)   The information contained in the Report fairly presents, in  all
       material respects, the financial condition and results of
 operation of the
       Company.


Date:  November 15, 2004




/s/ L. Paul Latham
L. Paul Latham
President and Chief Executive Officer
  of Southwest Royalties, Inc., the
  Managing General Partner of
  Southwest Royalties Institutional Income Fund X-B, L.P.

                 CERTIFICATION PURSUANT TO            Exhibit 32.2
                          19 U.S.C. SECTION 1350,
                          AS ADOPTED PURSUANT TO
               SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


    In   connection  with  the  Quarterly  Report  of  Southwest  Royalties
Institutional Income Fund X-B, L. P. (the "Company") on Form 10-Q  for  the
period  ending September 30, 2004 as filed with the Securities and Exchange
Commission  on  the  date hereof (the "Report"), I,  Mel  G.  Riggs,  Chief
Financial Officer of the Managing General Partner of the Company,  certify,
pursuant  to 18 U.S.C.  1350, as adopted pursuant to  906 of the  Sarbanes-
Oxley Act of 2002, that:

     (1)  The Report fully complies with the requirements of section 13(a) or
       15(d) of the Securities Exchange Act of 1934; and

     (2)   The information contained in the Report fairly presents, in  all
       material respects, the financial condition and results of
operation of the
       Company.


Date: November 15, 2004




/s/ Mel G. Riggs
Mel G. Riggs
Vice President and Chief Financial Officer of
  Southwest Royalties, Inc., the
  Managing General Partner of
  Southwest Royalties Institutional Income Fund X-B, L.P.