Dimension X was an NBC radio program broadcast mostly on an unsponsored, sustaining basis from April 8, 1950, to September 29, 1951.

Fred Wiehe and Edward King were the directors, and Norman Rose was heard as both announcer and narrator, opening the show with: "Adventures in time and space... told [or transcribed] in future tense..." For two months, beginning on July 7, 1950, the series was sponsored by Wheaties.

[1] Preceded by Mutual's 2000 Plus (1950–52), Dimension X was not the first adult science fiction series on radio,[2] but the acquisition of previously published stories immediately gave it a strong standing with the science fiction community, as did the choice of established writers within the genre: Isaac Asimov, Robert Bloch, Ray Bradbury, Fredric Brown, Robert A. Heinlein, Murray Leinster, H. Beam Piper, Frank M. Robinson, Clifford D. Simak, William Tenn, Jack Vance, Kurt Vonnegut, Jack Williamson and Donald A. Wollheim.

In Science Fiction Television (2004), M. Keith Booker wrote: The series opened with "The Outer Limit," Ernest Kinoy's adaptation of Graham Doar's short story from The Saturday Evening Post (December 24, 1949) about alien contact.

A week later (April 15, 1950), the program presented Jack Williamson's most famous story, "With Folded Hands," first published in the July 1947 issue of Astounding Science Fiction.