As with the previous sequel, the musical score was composed and conducted by Ken Thorne, using the Superman theme and most other themes from the first film composed by John Williams, but this time around there is more original music by Thorne than the Williams re-arrangements. To capitalize on the popularity of synthesizer pop, Giorgio Moroder was hired to create songs for the film, though their use in the film is minimal.
According to the score analysis at supermancinema.co.uk[dead link], Ken Thorne contributed 66% of new material for the film, the remainder being derived from John Williams's themes. Lois Lane's theme is not present as she is not in the film for more than a few minutes.
Superman III was the first of the films to have a score and soundtrack on the same release. Side A was devoted to 14 minutes of Ken Thorne's score (including new material such as a comedic cue that corresponds with the opening slapstick sequence, a theme for Richard Pryor's character, Gus Gorman, and the climactic fight between Clark Kent and Evil Superman).
Side B was devoted to music by pop mogul Giorgio Moroder. He specifically contributed a synthesized version of the "Superman II March", but wasn't used in the film. He also created a new love theme for Clark and Lana Lang. He contributed three other songs that appear mostly in instrumentals in the film, the most prominent being "They Won't Get Me" for Roger Miller, which appears when Gus shows up in a baby blue ten gallon hat to bribe Brad with alcohol. A CD of this album coupled with the album from Superman II was released in Japan.