The Incredible Melting Man (1977)
The Incredible Melting Man is a 1977 American science fiction horror film about an astronaut whose body begins to melt after he is exposed to radiation during a space flight to Saturn, driving him to commit murders and consume human flesh to survive. Written and directed by William Sachs, the film starred Alex Rebar as Steve West, the antagonist of the title, alongside Burr DeBenning as a scientist trying to help him, and Myron Healey as a United States Air Force general seeking to capture him. It has been described as a remake of First Man into Space (1959).
More at Wikipedia.