Born on July 14th, 1934 in Mt Holly, New Jersey, he studied at the Katharine Gibbs School of Art from 1953 until 1956 before joining Mayhew Peakes Inc. as a graphic designer. Dissatisfied with his progress he resigned in 1962 and moved to California where he married Marjorie in 1966. The new Californian environment gave him unrestricted floral subjects for his painting and he painted furiously to make up for the lost time he felt he had spent in Philadelphia. It was important to him that art was available to the general public. He appreciated that most people could not afford thousands of Dollars for original works and, often to his own financial detriment, he strived to keep his sale prices low.

Although generally shy and unassuming, he was a founder member of the Art Workers Coalition and very active in promoting the rights of artists. He was awarded the Brown Hammerson Medal of Honour for services to art in 1986.

One of the most prolific painters of the 1970s and 1980s, Robert Cox established a huge reputation in the United States for his almost neo-Victorian style and his early adoption of the pallet knife in creating stylised flowers. His work is represented in many American museums, galleries and private collections as well as having been frequently exported to Europe and Australia and has been auctioned at Christies, Bonhams and Cheffins.

Robert Cox died on June 18th, 2001 in Escondido, California after a long illness. His wife, Marjorie, and his daughters, Kate and Ginny, survived him.