Written by the band in 1969, it is said by the band members themselves to have been inspired by a riff featured in a song by Purple contemporaries It's a Beautiful Day, called "Bombay Calling". The riff was played on violins and much faster in tempo.
"Child in Time" is an essentially simple composition, featuring an organ intro, three power chords, and a two minute long solo. Lyrically dark, Vocalist Ian Gillan utilizes his full vocal range and goes from quiet singing to loud, high-pitched, banshee-esque screaming. Guitarist Ritchie Blackmore comes in with a slow solo, which builds up to a fast-pace playing and then ends abruptly, with the whole song cycle starting over again. Blackmore is normally associated with playing a Fender Stratocaster, however, he played a Gibson ES-335 on the studio version of the song.
A staple of the Deep Purple live concerts in 1970–73, the song has not been featured regularly at concerts since the reunion of the line up in 1993. Gillan cites many personal reasons for leaving the song out, but it is likely that, given his advancing years, the song is becoming increasingly difficult to perform without sampled vocal backings. Its last appearance in Deep Purple's live set was at Harrogate in 2002. In that performance, high-pitched guitar was used to cover up Gillan's now-limited vocal range during the "screaming" parts. A similar technique is used on current live performances of "Space Truckin'".