"Set the Controls for the Heart of the Sun" is a song by the English rock band Pink Floyd, appearing on their second album, A Saucerful of Secrets (1968). It was written by Roger Waters, taking lyrics from a Chinese poetry book, and features a drum part by Nick Mason played with timpani mallets. It is the only song recorded by Pink Floyd to feature material from all five band members, as there are several different guitar parts recorded by both David Gilmour and Syd Barrett, although the guitar parts are buried in the mix.

The song was regularly performed between 1967 and 1973 and can be heard on the live disc of the 1969 album Ummagumma and seen in the 1972 movie Pink Floyd: Live at Pompeii. Waters has also played the song on several solo tours, as has Mason.

The song was written by Roger Waters in mid-1967, who came up with a riff over which he could sing a melody within his vocal range. One of the group's managers, Peter Jenner said it was the first song that Waters wrote that he thought was a similar quality to those by Syd Barrett.

Waters borrowed the lyrics from a book of Chinese poetry from the Tang dynasty (which was later identified as the book Poems of the late T'ang, translated by A.C. Graham). The title was derived from the 1965 novel The Fireclown by Michael Moorcock. Among the borrowed lines from Chinese poetry (as translated by Graham) were those written by Li He, whose poem "Don't Go Out of the Door" contains the line "Witness the man who raved at the wall as he wrote his questions to Heaven" (公看呵壁書問天); and Li Shangyin, whose poetry contained the lines "watch little by little the night turns around" (暫見夜闌干), "countless the twigs which tremble in dawn" (撼曉幾多枝) and "one inch of love is one inch of ashes" (一寸相思一寸灰).

Recording started on 8 August 1967 at Abbey Road Studios, including the lead vocal on 23 October, and overdubs continuing through to January and February 1968. According to guitarist David Gilmour, the studio version of the song contained minor guitar work both from him and Syd Barrett, making "Set the Controls for the Heart of the Sun" the only Pink Floyd song that features all five band members. Keyboardist Richard Wright made prominent use of the Farfisa organ, and also played vibraphone on the track. Drummer Nick Mason enjoyed recording the track as it allowed him to emulate Chico Hamilton's drumming on "Blue Sands", using mallets, as seen in the 1958 film Jazz on a Summer's Day.

The track was planned for release as a single, with "Scream Thy Last Scream", on 8 September, before this was vetoed by the band's record company, EMI. It is one of two songs from A Saucerful of Secrets which appear on the 2001 compilation album Echoes: The Best of Pink Floyd (the other being "Jugband Blues").

In a negative review of A Saucerful of Secrets, Jim Miller of Rolling Stone described "Set the Controls for the Heart of the Sun", along with "Let There Be More Light", as "boring melodically, harmonically, and lyrically." Miller further described the production work as "not as glittery as the first album's, and the instrumental work is shoddy and routine. Miller also described the track as too long.

Mason later gave a positive view of the song, saying it was "the most interesting ... in relation to what we were doing at the time".