Dimension X was an NBC radio program broadcast on an unsponsored, sustaining basis from April 8, 1950 to September 29, 1951. The first 13 episodes were broadcast live, and the remainder were pre-recorded. Fred Wiehe and Edward King were the directors, and Norman Rose was heard as both announcer and narrator (his famous opening: "Adventures in time and space- told in future tense...").
Dimension X was not the first adult science fiction series on radio, but the acquisition of previously published stories immediately gave it a strong standing with the science fiction community.
In Science Fiction Television (2004), M. Keith Booker wrote:
It was not until the 1950s that science fiction radio really hit its stride, even as science fiction was beginning to appear on television as well. Radio programs such as Mutual's 2000 Plus and NBC's Dimension X were anthology series that offered a variety of exciting tales of future technology, with a special focus on space exploration (including alien invasion), though both series also often reflected contemporary anxieties about the dangers of technology.
With a five-month hiatus from January 1951 to June 1951, the series spanned 17 months. All 50 episodes of the series survived and can be heard today. Later, NBC's X Minus One (1955-58) utilized many of the same actors and scripts.