The business grew, became a franchise, and eventually became known as Gino's Hamburgers.
"During his time with Gino's, Mitch Thomas helped make Gino's like family to the millions of people that ate there over the years," his son said.
Gino's relationships with all the major Philadelphia sports franchises, which Mr. Thomas helped to cement by working behind the scenes, were integral to the chain's success, his son said.
By the time it was sold in 1982, the chain had 313 company-owned locations. The buyer, Marriott International, renamed the eateries Roy Rogers restaurants.
Born in Atlantic City, Mr. Thomas graduated from Atlantic City High School in 1941 and the University of Pennsylvania in 1949 with a degree in English.
He received a certificate in advertising and public relations in 1950 from the Charles Morris Price School of Advertising and Journalism.
During World War II, Mr. Thomas was inducted into the Army in June 1943. He was deployed to Italy with the 370th Infantry Regimental Combat Team in July 1944.
He participated in three major battles and was awarded a Bronze Star for heroic achievement in battle and honorably discharged in December 1945.
After the war, he worked at newspapers in Atlantic City, Norfolk, Va., Baltimore, and Philadelphia, where he was city editor at the Philadelphia Tribune from 1953 to 1957.
He was an official of many organizations, including the Southeastern Pennsylvania Chapter - American Red Cross; March of Dimes, Southeastern Pennsylvania; National Adoption Center; Salvation Army; and the Philadelphia Police Athletic League.
He was inducted into the Philadelphia Public Relations Association hall of fame and was named an outstanding graduate of the Charles Morris Price School of Advertising and Journalism.
He was devoted to his family, his faith, and fishing in Delaware Bay and at the Jersey Shore, his son said.
In addition to his son, Mr. Thomas is survived by his wife of 60 years, the former Pearline Bell; sons Robert M. Jr., Richard M., and Randall M.; a daughter, Ariane M.; and five grandchildren.
Visitation is set for 9:30 a.m. Monday, March 17, at the Church of Our Lady of Lourdes, 63d Street and Lancaster Avenue, Philadelphia, followed by a 10:30 a.m. Funeral Mass. Interment will be in Holy Sepulchre Cemetery.