EXHIBIT 24 POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that each of the undersigned Directors of Aluminum Company of America (the "Company") hereby constitutes and appoints ROBERT G. WENNEMER, EARNEST J. EDWARDS and DENIS A. DEMBLOWSKI, or any of them, his or her true and lawful attorneys and agents to do any and all acts and things and execute any and all instruments which said attorneys and agents, or any of them, may deem necessary or advisable or may be required to enable the Company to comply with the Securities Exchange Act of 1933, as amended, and any rules, regulations or requirements of the Securities and Exchange Commission in respect thereof, in connection with the registration under said Act of shares of common stock of the Company to be issued and distributed pursuant to the Long Term Stock Incentive Plan of the Company or any successor plan, including specifically, but without limiting the generality of the foregoing, power and authority to sign the name of each of the undersigned Directors of the Company in the capacity of Director thereof to any registration statement to be filed with the Securities Exchange Commission in respect of said Plan or successor plan and shares of common stock, or either of them, to any and all pre-effective amendments, post-effective amendments and supplements to any such registration statement, and to any instruments or documents filed as part of or in connection with any such registration statement or pre-effective amendments or post-effective amendments or supplements thereto; and the undersigned hereby ratifies and confirms all that said attorneys and agents, or any of them, shall do or cause to be done by virtue hereof. IN WITNESS WHEREOF, the undersigned have subscribed these presents on the date set opposite their names below. /s/ Kenneth W. Dam 5/8/97 /s/ Sir Arvi Parbo 5/8/97 Kenneth W. Dam Sir Arvi Parbo /s/ Joseph T. Gorman 5/8/97 /s/ Henry B. Schacht 5/8/97 Joseph T. Gorman Henry B. Schacht /s/ Judith M. Gueron 5/8/97 /s/ Forrest N. Shumway 5/8/97 Judith M. Gueron Forrest N. Shumway /s/ Sir Ronald Hampel 5/8/97 /s/ Franklin A. Thomas 5/8/97 Sir Ronald Hampel Franklin A. Thomas /s/ John P. Mulroney 5/8/97 /s/ Marina v.N. Whitman 5/8/97 John P. Mulroney Marina v.N. Whitman