Gilbert B. Lessenco, a Washington lawyer whose specialties included business regulation and government affairs, and a political activist who raised money and advised Democratic Party politicians, died July 30 at a hospital in Bethesda. He was 85.

The cause was complications from heart ailments and pneumonia, said a sister-in-law, Roslyn Beitler.

At his death, Mr. Lessenco was counsel at Thompson Hine in Washington, where he focused on trade association, corporate law and product liability litigation. Earlier, he was managing partner at Semmes, Bowen & Semmes.

He also was a Washington lobbyist representing such firms as General Mills.

As a political activist, he hosted periodic political salons at his Bethesda home for more than 40 years. He was a mentor to Montgomery County Democrat Mike Barnes early in the former Congress member’s political career. At his political gatherings, Lessenco raised money for Vice President Walter Mondale, Montgomery County Executive Charles W. Gilchrist and Barnes.

He was a former chairman of the Washington Suburban Sanitary Commission, the water and sewer agency for Montgomery and Prince George’s counties.

Gilbert Barry Lessenco was born June 19, 1929, in Baltimore. He graduated from Johns Hopkins University in 1950 and from Harvard Law School in 1953. He served in the Air Force from 1953 to 1955.

From 1955 to 1990, he practiced with the Washington law firm of Wilner & Scheiner. He was with Semmes, Bowen & Semmes from 1990 to 1996.

He was a member of Temple Sinai in Washington, and he helped raise money for the Strathmore arts center in North Bethesda.

His wife of 56 years, Elaine Beitler Lessenco, died in 2009. A daughter, Susan Lessenco, died in 1981, and a son, Robert Lessenco, died in 2005.

Survivors include a daughter, Amy Mowles of Edgewater, Md.