Dr. Haskell Philip Wald, 65, a retired senior economist and a director of the Federal Energy Regulatory Commission and a member of the President's Council of Economic Advisers in the Truman administration, died of cancer Friday at the National Institutes of Health. He lived in Bethesda.

Dr. Wald was a native of Worcester, Mass., and a 1938 graduate of Clark University there. He earned master's and doctoral degrees in economics at Harvard University.

He began his government career in Washington in 1938. He worked for the Federal Reserve System, the Treasury and Commerce departments and the National Security Resources Board.

From 1951 until 1953, he was on the Council of Economic Advisers. He also taught at American University.

Subsequently, he was a United Nations economic aide in Korea and Greece. He taught at Harvard Law School, returned to the Federal Reserve System and then joined the faculty of the New School for Social Research in New York. He moved back to Washington in 1962 and went to work for the Treasury.

From 1963 until 1977, he was chief economist at the Federal Power Commission. He joined the Federal Energy Regulatory Commission as senior economist and director of the Office of Regulatory Analysis in 1977. He retired in 1980.

Dr. Wald was a past president of Congregation Beth-El of Montgomery County and a member of B'nai B'rith, the American Jewish Committee and the Jewish Reconstructionist Foundation. He was also a member of the American Economic Association.

Survivors include his wife, Ruth J. of Bethesda; two sons, Dr. Alan M. Wald of Ann Arbor, Mich., and Michael E. of Bethesda; a daughter, Dr. Sharon Anne Krauss of Berkeley, Calif.; a brother, Leon of Worcester, and three grandchildren.