Robert Joseph O'Connor, 76, a retired colonel in the Army Judge Advocate General's Corps and a former member of the Armed Forces Board of Contract Appeals, died of a heart ailment June 8 at his home in Washington.

From 1961 to 1966, when he retired from the service, Col. O'Connor was a military member of the Board of Contract Appeals. From 1966 to 1968, he was a civilian member of it.

He was born in Allen, Neb., and reared in Sioux City, Iowa. He earned his law degree at Georgetown University and then returned to Sioux City, where he was in private law practice until 1942.

Col. O'Connor was called to active duty in the Army in that year and served in Washington and Guam during World War II. Subsequent assignments took him to Germany, the Army War College and to Washington.

His decorations included the Army Commendation Medal.

Col. O'Connor was a member of the American and Federal bar associations and the Institute of Military Law. He also was a member of the parish of the Shrine of the Most Blessed Sacrament.

His first wife, the former Kathryn E. Trainor, died in 1968.

Survivors include his wife, the former Margaret Carroll, of Washington; three children by his first marriage, Thomas T., of St. Petersburg, Fla., Mary K. Brinker of Ellicott City, Md., and Patricia Ann Cooper of Washington; five stepchildren, Margaret Carroll of Bethesda, Kate Cox and Clare Carroll of New York City, Ann Schmid of Wheaton, Ill., and Charles Carroll of Larchmont, N.Y., and 14 grandchildren.