Hot Butter was the alias of American keyboard virtuoso Stan Free. Free had been a member of the pioneering Moog synthesizer ensemble, the First Moog Quartet, and during their 1969 tour of the States they had used “Popcorn” as an encore. In 1972, remembering the positive response the song had received, Free released it as a single and it became a worldwide hit peaking at #5 in the UK and #9 in the US. It was one of the first pop hits to be entirely played by a synthesizer.

Since then, the spacey pop instrumental has appeared in many computer games and film soundtracks and in 2005 Crazy Frog had a #12 hit in the UK with a cover version.
The song was written by the German performer Gershon Kingsley, who was the leader of the First Moog Quartet and the first person to use the Moog synthesizer in live performance. He told Reuters in a telephone interview: “I am glad I was born in Germany and partook of German culture. Because whether you’re talking about Beethoven, Goethe or Wagner, it’s unique in the history of humankind.

Popcorn is a classical melody, it could easily be incorporated into a Bach piece. It’s so transparent – it’s like why you can’t change a Mozart melody. It took me five minutes. But I could never do it again.”
Unfortunately for Kingsley, he discovered that he had unwittingly sold half the publishing rights to the song before it became a hit. “It took a long time to get over that,” he told Reuters.
Kingsley was close to 50 by the time the tune became a hit, prompting disbelief among many that he had written it. He recalled: “When I went to pick up my first golden record in Germany, they said to me, ‘You wrote Popcorn?'”