The Rev. Robert P. Gainey, 75, pastor of Corinthian Baptist Church here for the last 40 years, died of pneumonia Saturday at Georgetown University Hospital.

Mr. Gainey was ordained in 1933 and served at Baptist churches in Virginia before moving here in 1936. After serving as pastor of First Baptist Church of Washington for three years, he was named pastor of Corinthian Baptist Church.

In 1957, Mr. Gainey was a keynote speaker at the National Baptist Convention. He was a former state vice president of the convention, a member of the board of trustees of the Washington Baptist Home, a member of the executive board and vice chairman of the foreign mission committee of the National Capital Baptist Convention.

He also held a number of offices with the Mount Bethel Baptist Association of the greater Washington area.

Mr. Gainey was born in King George County, Va. He graduated from the Washington Baptist Seminary here in 1944. In 1948, he earned a bachelor's degree in theology from Northwestern College in Washington and later recieved an honorary doctor of divinity degree from the Virginia Theological Seminary and College in Lynchburg, Va.

Survivors include his wife of 54 years, the former Elizabeth Steward, of Washington, and a brother, Thomas E., of Cleveland.