Ray Putnam Dinsmore (24 April 1893 – 26 October 1979^[1]) was a rubber scientist, known for pioneering the use of rayon as a reinforcing material in auto tires. In 1928, Dinsmore patented the first water-emulsion synthetic rubber in the United States.^[2] The material later became a staple of the rubber industry during the World War II shortage of natural rubber. Dinsmore worked for the Goodyear Tire and Rubber Company and developed Chemigum, an early synthetic rubber.^[3] Dinsmore hired noted rubber physicist Samuel D. Gehman, and he collaborated with Lorin Sebrell.^[4] His authored a popular review on the topic of rubber chemistry for the American Chemical Society's 75th Anniversary.^[5] Dinsmore served as chairman of the Rubber Division of the American Chemical Society in 1927. He received the 1947 Colwyn medal^[6] and was named the 1955 Charles Goodyear Medalist.

Dinsmore was educated at the Massachusetts Institute of Technology, completing a degree in chemical engineering at the age of 21.^[7] He entered the rubber industry in 1914.^[8] He was Vice President of Research and Development (1943-1961) and a Member of the Board of Directors (1960-1964) at the Goodyear Tire and Rubber Company.

He died on October 26, 1979.