The stunt was apparently part of a forthcoming television show, "Homemade Astronauts," that was scheduled to debut later this year on Discovery Inc.'s Science Channel.
Discovery confirmed the 64-year-old's death in a statement.
"It was always his dream to do this launch, and Science Channel was there to chronicle his journey," the company said.
The mishap was reported at 1:52 p.m. on private property in the Barstow area, San Bernardino County Sheriff-Coroner spokeswoman Cindy Bachman said by email. She did not identify Hughes.
"A man was pronounced deceased after the rocket crashed in the open desert during a rocket launch event," she said.
Sheriff's aviation investigators were looking into the accident.
In a statement last year, Discovery, Inc. described the forthcoming show as a look at "three self-financed teams with sky-high dreams, in their cosmic quest to explore the final frontier on shoe-string budgets."
Hughes' stunt Saturday was billed as part of a plan to raise money for another project, a planned launch to the border of space on a vehicle described as part rocket, part balloon, Discovery said.
The money-raising launch had a goal of reaching 5,000 feet into the sky aboard a "steam-powered rocket," the broadcaster said.
Hughes is known both for his homemade rockets and for his belief the earth is flat.
