George Francis (O-B) O'Brien, 86, who served in the D.C. fire department for 35 years until his retirement in 1954, died Sunday at the Veterans Administration Hospital here after a heart attack.

Mr. O'Brien joined the fire department in 1919. He was assigned to Truck Company No. 3 and then to the newly formed Engine Company No. 4. This was an all-black fire company and Mr. O'Brien served in it until 1945.

That year, he was assigned to Engine Company No. 27, another all-black unit that was organized at that time. Mr. O'Brien sang the "Star Spangled Banner" to the accompaniment of the U.S. Marine Band when the company was inaugurated.

At his retirement, Mr. O'Brien was a member of the fire inspector's office.

Mr. O'Brien was born in Washington and was a lifelong resident. He served in the Army in World War I and was sent to Hampton Institute in Hampton, Va.

A member of the American Legion, he was a past commander of James Reese Europe Post No. 5. He also was a Mason and a past master of Meridian Lodge No. 6, PHA. He belonged to the St. Paul AME Church in Washington and was a past member of its board of trustees and its senior and gospel choirs.

His wife, the former Nettie C. Norris, died in 1970.

He leaves no immediate survivors.