The song is built around a descending riff, with the dominant instrument being composer Syd Barrett's electric guitar, fed through an echo machine; the resultant sound has been likened to a "sinister" Duane Eddy.
[4] This is augmented by bowed bass and increasingly agitated organ and percussion effects.
[5] Though the lyric frequently refers to Lucifer Sam as a cat, some speculation has arisen as to whether this was in fact slang ("a hip cat") for a man, real or imagined, in some type of relationship with Barrett's then-girlfriend, Jenny Spires (referred to in the song as "Jennifer Gentle").
[5] However, Sam was simply Barrett's Siamese cat (and is referred to as such in the first line: "Lucifer Sam, Siam cat"); the track was originally called "Percy the Rat Catcher" during the recording sessions, which took place between April and June 1967.
[9] The track has also been covered by the Black Crowes, Electric Hellfire Club, the Minders, the Flaming Lips, True West, Jay Farrar, Love and Rockets,[10] Shockabilly, the Sadies, the Three O'Clock, MGMT, Spirits in the Sky, Unknown Mortal Orchestra, Obits (with different lyrics, as "Widow of my Dreams"), Cat's Eyes, Bauhaus, Southern Culture on the Skids, The Horrors and Chris & Cosey.