John Russell Mason, 81, librarian and curator of art emeritus at George Washington University, died of pneumonia Saturday at George Washington University. He had a stroke in January.

Mr. Mason, who was born in Philadelphia and grew up in Washington, where he graduated from Roosevelt High School, earned his bachelor's and master's degrees at GW in 1923 and 1925. But he began his career there as a student assistant in 1920 and remained on the faculty until 1966.

From 1923 to 1929, he was assistant librarian; from 1929 to 1933, he was associate librarian, and from 1933 until 1965 he was librarian. He had earned a degree in library science at Columbia University in 1933.

In 1944, while continuing his work as a librarian, Mr. Mason was named the university's curator of art. He held both positions until his former retirement in 1965, when he received emeritus status as librarian and curator. He stayed on until 1966.

Among the notable acquisitions to the GW art collection during Mr. Mason's tenure as curator was a Gilbert Stuart portrait of George Washington. In all Mr. Mason arranged 176 art exhibitions at the university.

In 1951, Mr. Mason received the university's Alumni Achievement Award. In 1974, a reading and study room in the library was named in his honor.

Mr. Mason, who lived in Washington, was a member of the American and D.C. library associations and of other professional groups. He also was a member of the American Guild of Organists, having served as GW's unofficial organist for many years.

He leaves no immediate survivors.

It is suggested that expressions of sympathy be in the form of contributions to the John Russell Mason Memorial Fund, George Washington University, Washington, 20052.