[1] The song was written by Paul Stanley and his frequent collaborator Desmond Child.
[1] Both "Let's Put the X in Sex" and "(You Make Me) Rock Hard" were recorded by Paul Stanley on his own in July 1988 at New York's Right Track Studios.
According to The Official Price Guide to Kiss Collectibles by Ingo Floren, the two songs let some fans wonder about the new musical direction of the band" because they "were produced with lots of keyboards over a dance-orientated beat".
[2] The song was released in the United States in October 1988 as the first single from the album Smashes, Thrashes & Hits.
The book also notes that some people compare this Kiss song to "Addicted to Love" by Robert Palmer.