CERTIFICATE OF DETERMINATION OF PREFERENCES
                                       OF
                      8 7/8% SERIES Y CUMULATIVE REDEEMABLE
                                 PREFERRED STOCK
                                       OF
                             PS BUSINESS PARKS, INC.
                [As Filed in the Office of the Secretary of State
                  of the State of California on July 12, 2000]


     The  undersigned,  David Goldberg and Jack E. Corrigan,  Vice President and
Secretary,  respectively,  of PS BUSINESS PARKS, INC., a California corporation,
do hereby certify:

     FIRST: The Restated Articles of Incorporation of the Corporation  authorize
the  issuance  of  50,000,000  shares of stock  designated  "preferred  shares,"
issuable  from time to time in one or more series,  and  authorize  the Board of
Directors  to fix the  number of shares  constituting  any such  series,  and to
determine or alter the dividend rights, dividend rate, conversion rights, voting
rights, right and terms of redemption  (including sinking fund provisions),  the
redemption price or prices and the liquidation preference of any wholly unissued
series of such preferred shares, and the number of shares  constituting any such
series.

     SECOND:  The  Board of  Directors  of the  Corporation  did duly  adopt the
resolutions  attached hereto as Exhibit A and  incorporated  herein by reference
authorizing and providing for the creation of a series of preferred shares to be
known as "8 7/8% Series Y Cumulative  Redeemable  Preferred Stock" consisting of
480,000 shares, none of the shares of such series having been issued.

     We further  declare under penalty of perjury under the laws of the State of
California  that the matters set forth in this  certificate are true and correct
of our own knowledge.

     IN WITNESS  WHEREOF,  the undersigned  have executed this  certificate this
12th day of July, 2000.

                                                  /s/ DAVID GOLDBERG
                                                  ------------------------------
                                                  David Goldberg, Vice President


                                                  /s/ JACK E. CORRIGAN
                                                  ------------------------------
                                                  Jack E. Corrigan, Secretary



                                    EXHIBIT A

                      RESOLUTION OF THE BOARD OF DIRECTORS
                           OF PS BUSINESS PARKS, INC.

                    ESTABLISHING A SERIES OF 8 7/8% SERIES Y
                      CUMULATIVE REDEEMABLE PREFERRED STOCK


     RESOLVED  that  pursuant  to the  authority  conferred  upon  the  Board of
Directors  by Article  III of the  Restated  Articles of  Incorporation  of this
Corporation,  there is hereby  established a series of the authorized  preferred
shares of this  Corporation  having a par value of $.01 per share,  which series
shall be designated  "8 7/8% Series Y Cumulative  Redeemable  Preferred  Stock,"
shall consist of 480,000 shares and shall have the following rights, preferences
and privileges:

     1. Rank.  The 8 7/8% Series Y Cumulative  Redeemable  Preferred  Stock (the
"Series Y Preferred  Stock") will, with respect to distributions and rights upon
voluntary  or  involuntary   liquidation,   winding-up  or  dissolution  of  the
Corporation,  or both, rank senior to all classes or series of Common Shares and
to all  classes  or  series  of  equity  securities  of the  Corporation  now or
hereafter authorized,  issued or outstanding,  other than any class or series of
equity securities of the Corporation expressly designated as ranking on a parity
with or senior to the Series Y Preferred  Stock as to  distributions  and rights
upon  voluntary or  involuntary  liquidation,  winding-up or  dissolution of the
Corporation. For purposes of this Certificate of Determination, the term "Parity
Preferred  Stock" shall be used to refer to any class or series of capital stock
of the Corporation now or hereafter authorized,  issued or outstanding expressly
designated by the  Corporation to rank on a parity with Series Y Preferred Stock
with  respect  to  distributions   and  rights  upon  voluntary  or  involuntary
liquidation,  winding-up  or  dissolution  of  the  Corporation  (including  the
Corporation's  9 1/4%  Cumulative  Preferred  Stock,  Series A, 8 7/8%  Series B
Cumulative  Redeemable  Preferred  Stock, 8 3/4% Series C Cumulative  Redeemable
Preferred Stock and 8 7/8% Series X Cumulative  Redeemable Preferred Stock). For
purposes of the preceding sentence,  "capital stock" means any equity securities
(including  Common Shares and Preferred Stock),  shares,  participation or other
ownership  interests  (however  designated)  and any  rights  (other  than  debt
securities convertible into or exchangeable for equity securities) or options to
purchase any of the foregoing.

     2.  Distributions  Rights.  (a)  Payment of  Distributions.  Subject to the
rights of holders of Parity Preferred Stock as to the payment of  distributions,
holders of Series Y  Preferred  Stock shall be entitled to receive the  Series Y
Priority  Return,  when,  as and if  declared by the Board of  Directors  of the
Corporation,  out of funds legally  available for the payment of  distributions.
Such distributions  shall be cumulative,  shall accrue from the original date of
issuance of the Series Y  Preferred  Stock and will be payable (A)  quarterly in
arrears,  on March  31,  June 30,  September  30 and  December  31 of each  year
commencing  on the  last  day of the  calendar  quarter  following  the  date of
issuance of such stock and, (B) in the event of a redemption,  on the redemption
date (each a "Series Y  Preferred  Stock  Distribution  Payment  Date").  If any
Preferred  Stock  Distribution  Payment  Date is not a Business  Day (as defined
herein),  then payment of the distribution to be made on such date shall be made
on the Business Day  immediately  preceding  such Preferred  Stock  Distribution
Payment  Date in each  case with the same  force  and  effect as if made on such
date.  Distributions on the Series Y Preferred Stock will be made to the holders
of record of the Series Y  Preferred  Stock on the  relevant  record dates to be
fixed by the Board of Directors of the Corporation,  which record dates shall in
no  event  be more  than 45 days or  less  than 15 days  prior  to the  relevant
Series Y Preferred Stock Distribution  Payment Date (each a "Distribution Record
Date").

     For   purposes  of this  Certificate of Determination,  the following terms
shall   have  the meanings  set forth  herein:    (i)   "Liquidation Preference"
shall  mean,  with  respect to  the Series  Y Preferred Stock,  $25.00 per share
of  Series  Y  Preferred Stock,  plus the amount  of any  accumulated and unpaid
Series Y Priority Return (as  hereinafter defined) with  respect to such  share,
whether or not declared,  minus  any  distributions  in  excess  of the Series Y
Priority Return that has occurred with respect to such Series Y Perferred Units,

to the date of payment;  (ii)  "Series Y Priority  Return"  shall mean an amount
equal to 8 7/8% per annum of the  Liquidation  Preference  per share of Series Y
Preferred  Stock,  commencing  on the date of issuance of such share of Series Y
Preferred Stock,  determined on the basis of a 365-day year (and actual days for
any period),  cumulative to the extent not distributed on any Series Y Preferred
Stock  Distribution  Payment Date; and (iii) "Business Day" shall mean each day,
other  than  a  Saturday  or a  Sunday,  which  is not a day  on  which  banking
institutions in New York, New York are authorized or required by law, regulation
or executive order to close.

     (b) Prohibition on  Distributions.  No distributions on Series Y  Preferred
Stock shall be authorized by the Board of Directors of the  Corporation  or paid
or set apart for  payment by the  Corporation  at any such time as the terms and
provisions of any agreement of the Corporation  including any agreement relating
to  indebtedness,  prohibits  such  authorization,  payment or setting apart for
payment or  provides  that such  authorization,  payment  or  setting  apart for
payment would  constitute a breach  thereof or a default  thereunder,  or to the
extent that such  authorization  or payment shall be restricted or prohibited by
law.

     (c) Distributions Cumulative. Distributions on the Series Y Preferred Stock
will accrue  whether or not the terms and  provisions  of any  agreement  of the
Corporation,  including any agreement  relating to its  indebtedness at any time
prohibits the current payment of  distributions,  whether or not the Corporation
has earnings,  whether or not there are funds legally  available for the payment
of such  distributions  and whether or not such  distributions are authorized or
declared.  Accrued but unpaid distributions on the Series Y Preferred Stock will
accumulate as of the Series Y Preferred Stock Distribution Payment Date on which
they first  become  payable.  Distributions  on account of arrears  for any past
distribution  periods may be declared and paid at any time, without reference to
a regular  Series Y  Preferred  Stock  Distribution  Payment  Date to holders of
record of the Series Y  Preferred Stock on the record date fixed by the Board of
Directors  which  date shall not be more than 45 days or less than 15 days prior
to the  payment  date.  Accumulated  and  unpaid  distributions  will  not  bear
interest.

     (d) Priority as to  Distributions.  (i) So long as any  Series Y  Preferred
Stock  is  outstanding,  no  distribution  of cash or  other  property  shall be
authorized,  declared,  paid or set apart for payment on or with  respect to any
class or series of  Common  Shares or any class or series of other  stock of the
Corporation  ranking  junior as to the payment of  distributions  or rights upon
voluntary  or  involuntary   dissolution,   liquidation  or  winding-up  of  the
Corporation to the Series Y  Preferred Stock (such Common Shares or other junior
stock,  collectively,  "Junior Stock"),  nor shall any cash or other property be
set aside for or applied to the purchase,  redemption or other  acquisition  for
consideration of any Series Y Preferred Stock, any Parity Preferred Stock or any
Junior  Stock,  unless,  in each  case,  all  distributions  accumulated  on all
Series Y  Preferred  Stock and all  classes  and  series of  outstanding  Parity
Preferred  Stock  have  been  paid in full.  The  foregoing  sentence  shall not
prohibit  (i)  distributions  payable  solely  in  Junior  Stock,  and  (ii) the
conversion of Series Y  Preferred Stock,  Junior Stock or Parity Preferred Stock
into stock of the Corporation  ranking junior to the Series Y Preferred Stock as
to distributions.

     (ii)  So  long as  distributions  have  not  been  paid  in full  (or a sum
sufficient  for such full  payment  is not  irrevocably  deposited  in trust for
payment) upon the Series Y  Preferred  Stock, all  distributions  authorized and
declared  on  the  Series Y  Preferred  Stock  and  all  classes  or  series  of
outstanding  Parity  Preferred  Stock  with  respect to  distributions  shall be
authorized  and  declared  so that the amount of  distributions  authorized  and
declared per share of Series Y  Preferred Stock and such other classes or series
of Parity  Preferred  Stock shall in all cases bear to each other the same ratio
that accrued  distributions  per share on the Series Y  Preferred Stock and such
other classes or series of Parity  Preferred  Stock (which shall not include any
accumulation in respect of unpaid  distributions for prior distribution  periods
if such  class or  series  of  Parity  Preferred  Stock  do not have  cumulative
distribution rights) bear to each other.

     (e) No Further  Rights.  Holders of Series Y  Preferred  Stock shall not be
entitled  to any  distributions,  whether  payable in cash,  other  property  or
otherwise, in excess of the full cumulative distributions described herein.

     3. Liquidation.  (a) Payment of Liquidating  Distributions.  Subject to the
rights of holders of Parity  Preferred  Stock  with  respect to rights  upon any
voluntary   or   involuntary    liquidation,    dissolution   or  winding-up  of

the Corporation and subject to any series of capital stock ranking senior to the
Series  Y  Preferred  Stock  with  respect  to  rights  upon  any  voluntary  or
involuntary  liquidation,  dissolution  or  winding-up of the  Corporation,  the
holders of Series Y  Preferred  Stock  shall be  entitled  to receive out of the
assets of the  Corporation  legally  available for  distribution or the proceeds
thereof,  after  payment or  provision  for debts and other  liabilities  of the
Corporation, but before any payment or distributions of the assets shall be made
to  holders  of  Common  Shares  or any  other  class or series of shares of the
Corporation  that ranks junior to the Series Y Preferred Stock as to rights upon
liquidation,  dissolution or winding-up of the  Corporation,  an amount equal to
the Liquidation  Preference per share of Series Y Preferred  Stock. If upon such
voluntary or  involuntary  liquidation,  dissolution  or  winding-up,  there are
insufficient  assets to permit full payment of liquidating  distributions to the
holders of Series Y Preferred Stock and any Parity  Preferred Stock as to rights
upon liquidation,  dissolution or winding-up of the Corporation, all payments of
liquidating  distributions  on the  Series Y  Preferred  Stock  and such  Parity
Preferred  Stock shall be made so that the  payments on the  Series Y  Preferred
Stock and such Parity  Preferred Stock shall in all cases bear to each other the
same ratio that the respective  rights of the Series Y  Preferred Stock and such
other  Parity  Preferred  Stock  (which  shall not include any  accumulation  in
respect of unpaid  distributions for prior  distribution  periods if such Parity
Preferred Stock does not have cumulative  distribution rights) upon liquidation,
dissolution or winding-up of the Corporation bear to each other.

     (b)  Notice.   Written   notice  of  any  such   voluntary  or  involuntary
liquidation,  dissolution or winding-up of the Corporation,  stating the payment
date or dates when, and the place or places where, the amounts  distributable in
such circumstances shall be payable, shall be given by (i) fax and (ii) by first
class mail,  postage pre-paid,  not less than 10 and not more than 60 days prior
to the  payment  date stated  therein,  to each  record  holder of the  Series Y
Preferred  Stock at the  respective  addresses of such holders as the same shall
appear on the share transfer records of the Corporation.

     (c) No Further Rights.  After payment of the full amount of the liquidating
distributions  to which they are  entitled,  the holders of  Series Y  Preferred
Stock  will  have no  right  or  claim  to any of the  remaining  assets  of the
Corporation.

     (d)  Consolidation,  Merger or Certain  Other  Transactions.  The voluntary
sale,  conveyance,  lease,  exchange  or  transfer  (for cash,  shares of stock,
securities or other  consideration)  of all or substantially all of the property
or  assets  of the  Corporation  to,  or the  consolidation  or  merger or other
business combination of the Corporation with or into, any corporation,  trust or
other  entity (or of any  corporation,  trust or other  entity  with or into the
Corporation)  or a statutory  share exchange shall not be deemed to constitute a
liquidation, dissolution or winding-up of the Corporation.

     4. Redemption.  (a) Right of Optional  Redemption.  The Series Y  Preferred
Stock may not be redeemed  prior to July 12,  2005.  On or after such date,  the
Corporation  shall have the right to redeem the  Series Y  Preferred  Stock,  in
whole  (but not in part),  at any  time,  upon not less than 30 nor more than 60
days'  written  notice,  at a redemption  price,  payable in cash,  equal to the
Liquidation Preference (the "Series Y Redemption Price").

     (b)  Limitation  on  Redemption.  The  redemption  price  of  the  Series Y
Preferred  Stock will be  payable  solely to the extent  such  payment  would be
permitted as a distribution under the California Corporations Code.

     (c) Procedures for Redemption.  (i) Notice of redemption will be (i) faxed,
and (ii) mailed by the Corporation,  postage prepaid,  not less than 30 nor more
than 60 days prior to the redemption date,  addressed to the respective  holders
of record of the  Series Y  Preferred  Stock to be redeemed at their  respective
addresses as they appear on the transfer records of the Corporation.  No failure
to give or defect in such notice shall  affect the  validity of the  proceedings
for the  redemption of any Series Y  Preferred  Stock except as to the holder to
whom such notice was  defective  or not given.  In  addition to any  information
required  by law or by the  applicable  rules of any  exchange  upon  which  the
Series Y Preferred Stock may be listed or admitted to trading,  each such notice
shall state:  (i) the  redemption  date,  (ii) the redemption  price,  (iii) the
number of shares of Series Y  Preferred Stock to be redeemed,  (iv) the place or
places where such shares of Series Y  Preferred  Stock are to be surrendered for

payment  of the  redemption  price,  (v)  that  distributions  on  the  Series Y
Preferred  Stock to be redeemed will cease to accumulate on such redemption date
and (vi) that payment of the  redemption  price and any  accumulated  and unpaid
distributions  will be made upon  presentation  and  surrender of such  Series Y
Preferred Stock.

     (ii) If the Corporation gives a notice of redemption in respect of Series Y
Preferred Stock (which notice will be irrevocable) then, by 12:00 noon, New York
City time, on the redemption date, the Corporation  will deposit  irrevocably in
trust for the  benefit of the  Series Y  Preferred  Stock being  redeemed  funds
sufficient  to pay the  applicable  Series Y  Redemption  Price,  and will  give
irrevocable  instructions and authority to pay such Series Y Redemption Price to
the holders of the Series Y  Preferred  Stock upon surrender of the  certificate
evidencing the Series Y  Preferred Stock by such holders at the place designated
in the notice of redemption. On and after the date of redemption,  distributions
will cease to accumulate on the Series Y  Preferred Stock called for redemption,
unless the Corporation  defaults in the payment  thereof.  If any date fixed for
redemption  of Series Y  Preferred  Stock is not a Business Day, then payment of
the  redemption  price payable on such date will be made on the next  succeeding
day that is a Business Day (and without any interest or other payment in respect
of any such delay)  except that, if such Business Day falls in the next calendar
year,  such payment will be made on the immediately  preceding  Business Day, in
each case  with the same  force  and  effect  as if made on such date  fixed for
redemption.  If payment of the Series Y  Redemption  Price or any accumulated or
unpaid  distributions  in respect of the Series Y  Preferred Stock is improperly
withheld  or  refused  and not paid by the  Corporation,  distributions  on such
Series Y   Preferred  Stock  will  continue  to  accumulate  from  the  original
redemption  date to the date of payment,  in which case the actual  payment date
will be considered the date fixed for redemption for purposes of calculating the
applicable Series Y Redemption Price.

     (d) Status of Redeemed  Stock.  Any Series Y  Preferred Stock that shall at
any time have been  redeemed  shall  after such  redemption,  have the status of
authorized  but unissued  Preferred  Stock,  without  designation as to class or
series until such shares are once more designated as part of a particular  class
or series by the Board of Directors.

     5. Voting Rights. (a) General. Holders of the Series Y Preferred Stock will
not have any voting rights, except as set forth below.

     (b) Right to Elect  Directors.  If the  Corporation  shall fail to pay full
cumulative  dividends  on the shares of Series Y  Preferred  Stock or any of its
preferred  shares for six quarterly  dividend  payment  periods,  whether or not
consecutive (a "Dividend  Default"),  the holders of all  outstanding  preferred
shares,  voting as a single class without regard to series,  will be entitled to
elect two  Directors  until  full  cumulative  dividends  for all past  dividend
payment  periods on all  preferred  shares have been paid or declared  and funds
therefor  set apart for  payment.  Such right to vote  separately  as a class to
elect Directors shall, when vested,  be subject,  always, to the same provisions
for the vesting of such right to elect  Directors  separately  as a class in the
case of future Dividend Defaults. At any time when such right to elect Directors
separately as a class shall have so vested,  the Corporation may call, and, upon
the  written  request of the holders of record of not less than 20% of the total
number of preferred  shares of the Corporation then  outstanding,  shall call, a
special  meeting of stockholders  for the election of Directors.  In the case of
such a written request,  such special meeting shall be held within 90 days after
the  delivery of such  request  and, in either  case,  at the place and upon the
notice provided by law and in the Bylaws of the  Corporation;  provided that the
Corporation shall not be required to call such a special meeting if such request
is received less than 120 days before the date fixed for the next ensuing Annual
Meeting of  Shareholders  of the  Corporation  and the holders of all classes of
outstanding  preferred  shares  are  afforded  the  opportunity  to  elect  such
Directors  (or  fill  any  vacancy)  at such  Annual  Meeting  of  Shareholders.
Directors  elected as  aforesaid  shall serve  until the next Annual  Meeting of
Shareholders of the Corporation or until their  respective  successors  shall be
elected and qualified.  If, prior to the end of the term of any Director elected
as aforesaid,  a vacancy in the office of such  Director  shall occur during the
continuance  of  a  Dividend  Default  by  reason  of  death,  resignation,   or
disability,  such  vacancy  shall  be  filled  for  the  unexpired  term  by the
appointment  of a new Director for the unexpired  term of such former  Director,
such appointment to be made by the remaining Director elected as aforesaid.

     (c) Certain Voting Rights.  So long as any Series Y  Preferred Stock remain
outstanding,  the Corporation  shall not,  without the  affirmative  vote of the
holders of a majority of the Series Y  Preferred Stock  outstanding at the time,
(i)  designate or create,  or increase the  authorized  or issued amount of, any
class or series of shares  ranking  prior to the Series Y  Preferred  Stock with
respect to payment of distributions or rights upon  liquidation,  dissolution or
winding-up or reclassify any authorized  shares of the Corporation into any such
shares,  or create,  authorize or issue any obligations or security  convertible
into or  evidencing  the right to purchase  any such shares,  (ii)  designate or
create,  or increase the  authorized or issued  amount of, any Parity  Preferred
Stock or  reclassify  any  authorized  shares of the  Corporation  into any such
shares,  or create,  authorize or issue any obligations or security  convertible
into or evidencing the right to purchase any such shares, but only to the extent
such Parity  Preferred  Stock is issued to an  Affiliate of the  Corporation  on
terms that differ  from the terms of any Parity  Preferred  Stock  issued to the
public or  non-Affiliates  of the Corporation,  or (iii) either (A) consolidate,
merge into or with, or convey,  transfer or lease its assets substantially as an
entirety,  to any corporation or other entity, or (B) amend, alter or repeal the
provisions  of  the  Corporation's   Charter   (including  this  Certificate  of
Determination)  or By-laws,  whether by merger,  consolidation or otherwise,  in
each case that would materially and adversely affect the powers, special rights,
preferences,  privileges or voting power of the Series Y  Preferred Stock or the
holders  thereof;  provided,  however,  that with respect to the occurrence of a
merger,  consolidation or a sale or lease of all of the Corporation's  assets as
an entirety,  so long as (a) the  Corporation  is the  surviving  entity and the
Series Y  Preferred Stock remains  outstanding with the terms thereof unchanged,
or (b) the resulting,  surviving or transferee entity is a corporation organized
under the laws of any state and  substitutes  the Series Y  Preferred  Stock for
other preferred stock having substantially the same terms and same rights as the
Series Y Preferred Stock, including with respect to distributions, voting rights
and rights upon liquidation,  dissolution or winding-up,  then the occurrence of
any such event  shall not be deemed to  materially  and  adversely  affect  such
rights,  privileges  or voting  powers of the holders of the Series Y  Preferred
Stock;  and  provided,  further,  that any increase in the amount of  authorized
Preferred  Stock or the  creation  or  issuance  of any other class or series of
Preferred Stock, or any increase in an amount of authorized shares of each class
or series,  in each case  ranking  either (a) junior to the  Series Y  Preferred
Stock with respect to payment of  distributions  and the  distribution of assets
upon  liquidation,  dissolution  or  winding-up,  or (b) on a  parity  with  the
Series Y  Preferred  Stock  with  respect to  payment  of  distributions  or the
distribution of assets upon liquidation, dissolution or winding-up to the extent
such Preferred  Stock is not issued to an Affiliate of the  Corporation on terms
that differ from the terms of any Parity Preferred Stock issued to the public or
non-Affiliates  of the  Corporation,  shall  not be  deemed  to  materially  and
adversely affect such rights, preferences, privileges or voting powers.

     The  affirmative  vote or consent of the holders of at least 66 2/3% of the
outstanding  shares of this  Series  and any other  series of  preferred  shares
ranking  on a parity  with this  Series as to  dividends  and upon  liquidation,
voting as a single class  without  regard to series,  will be required to issue,
authorize  or increase  the  authorized  amount of any class or series of shares
ranking prior to this Series as to dividends or upon  liquidation or to issue or
authorize any obligation or security  convertible  into or evidencing a right to
purchase any such security, but subject to Section 5(c)(ii) hereof, the Articles
of Incorporation  may be amended to increase the number of authorized  preferred
shares  ranking on a parity with or junior to this  Series or to create  another
class of  preferred  shares  ranking on a parity  with or junior to this  Series
without the vote of the holders of outstanding shares of this Series.

     6. Conversion.  The holders of the Series Y  Preferred Stock shall not have
any rights to convert  such  shares  into shares of any other class or series of
stock or into any other securities of, or interest in, the Corporation.

     7. No Sinking Fund. No sinking fund shall be established for the retirement
or redemption of Series Y Preferred Stock.

     8. No Preemptive  Rights. No holder of the Series Y  Preferred Stock of the
Corporation  shall,  as such holder,  have any preemptive  rights to purchase or
subscribe  for  additional  shares  of stock  of the  Corporation  or any  other
security of the Corporation which it may issue or sell.