Producer-director Stanley Kubrick initiated the project when he approached science fiction writer Arthur C. Clarke and suggested they team up. As early as the late '50s, when he made Paths of Glory (1957), Kubrick had been interested in the contrast between the closed, terrestrial view of things and a more open approach to human experience. Searching for a story about life outside the solar system, Kubrick bought the rights to half a dozen Clarke stories, but the author suggested that they focus only on one of them.

The main ideas for 2001: A Space Odyssey came from Arthur C. Clarke's 1950 short story "The Sentinel," about the discovery of a buried artifact on the moon that transmits a signal to an alien civilization. Also influential was Clarke's 1953 novel Childhood's End, in which an alien species visits the Earth to watch over the birth of the next stage in human evolution.

Clarke and director Stanley Kubrick were perfect collaborators. Both were fixated on technology, had high energy drives, were perfectionists, were insatiably curious and had similar ideas about spirituality. While neither believed in a particular religion, both believed that some supreme intelligence exists and can be defined scientifically.

It took 21 months (from April 1964-January 1966) to write 2001: A Space Odyssey. They started by writing a 130-page treatment. Then, Kubrick worked on the script while Clarke worked on the novel, but they met regularly to share ideas and direct each other's work. The differences between the two versions, besides reflecting the writers' differing viewpoints, grew from changes Kubrick made while translating the treatment into a script and other alterations made during shooting.

Initially, Clarke saw the project as more worldly in nature, calling it an extension of Kubrick's previous film, Dr. Strangelove: or How I Learned to Stop Worrying and Love the Bomb (1964). He even referred to it jokingly as Son of Strangelove. In his vision, the Star Child would return to Earth as the planet was being orbited by nuclear bombs and detonate them in an act of cosmic purification. He kept that ending for the novel version.

From the first, Kubrick saw the story as a mythic journey of transformation inspired by Homer's epic The Odyssey. It was his idea to change the title from Journey to the Stars to 2001: A Space Odyssey.

In early drafts, the monolith was to have contained a video screen on which the aliens would show the ape men how to use weapons. In addition, the deafening shriek made by the monolith on the Moon was clearly established as a radio emission sent to Jupiter. Kubrick ultimately decided that both ideas made the film's meaning too obvious.

Initially, MGM committed $6 million to the project. Due to Kubrick's meticulous working schedule in England, however, costs soon rose to almost double that amount.

Douglas Trumbull was a young painter working on NASA recruiting films when Kubrick recruited him to head up the picture's special effects team.

Kubrick hired Keir Dullea for the leading role of astronaut Dave Bowman without ever meeting him. He simply screened every film the actor had ever made, even the lesser pictures that had preceded his success in the independent hit David and Lisa (1962). The first time they actually met was when Dullea arrived for his first day of shooting. Although later critics would rail at his inexpressive performance, Dullea was happy to take a break from his typecasting as a misunderstood youth. "That image was driving me up the wall," he said, "and I stopped doing dramatic shows on television because of typecasting."