Bill Trumbull, who regaled Washington’s radio audiences for two decades as co-host of an easy-going and top-rated afternoon program, died of respiratory failure Jan. 10 at Prince William Hospital in Manassas. He was 77.

The death was confirmed by his former on-air partner, Chris Core. WMAL’s “Trumbull and Core” program was a staple of the weekday evening commute from 1976 to 1996. In all, Mr. Trumbull spent 36 years at the station and was usually on the air six days a week.

“Trumbull and Core” was a success because of the chemistry between the hosts. The program was a mix of news, pop music, listener and guest call-ins, and the occasional serious feature, offset by the hosts’ spontaneous humor — a combination that is increasingly rare in radio today.

Mr. Trumbull played characters such as B.B. Moody, a noted Nauga farmer. The pair would also compose humorous parody songs, such as “It’s Impassable” to memorialize a Washington snowstorm.

Core, now a commentator on WTOP (103.5 FM), said Mr. Trumbull’s skill at one-liners was essential for keeping the show moving. Mr. Trumbull once said that he joined a health club that was not yet open, but he kept in shape by paying the membership dues.

Mr. Trumbull spent almost all of his professional career on the radio in Washington. After a stint in the Army, during which he served as the master of ceremonies for the U.S. Army Band and Chorus based at Fort Myer in Arlington County, he was hired by WMAL (105.9 FM and 630 AM) as an announcer. He was introduced to the station’s management by an Army buddy, singer Steve Lawrence, who became an occasional call-in guest on Mr. Trumbull’s radio programs.

Mr. Trumbull also served for several years as an announcer on WMAL-TV, Washington’s ABC affiliate. The station later became WJLA.

After working solo on WMAL, Mr. Trumbull teamed up with newsman Ed Meyer on a program called “Two for the Road.” Core replaced Meyer, and the program became a ratings magnet, bookending WMAL’s popular and durable morning personalities, Frank Harden and Jackson Weaver.

William Dennis Trumbull was born in Westfield, Mass., on Dec. 11, 1934, and grew up in New England and Queens. He began his radio career in 1955 as a DJ at a pop-music station in Chicopee, Mass.

While working there, he met his future wife, the former Nancy Landry, who was employed by a bank in the same building. The couple celebrated their 55th wedding anniversary last year.

Besides his wife, of Bristow, survivors include two children, Navy Cmdr. Steve Trumbull of Bristow and Kim Kendziora of Burke; a sister; and four grandchildren. A son, William Trumbull, died in 1985.

Mr. Trumbull’s daughter recalled that as a child she contributed a review of a Muppet movie to her father’s program. His son Steve occasionally phoned the program with updates from Navy postings around the world.