The script for White Heat was based on a story written for the screen by Virginia Kellogg. She followed this film with another stark and brutal prison drama, with the added twist of setting it in a women's institution: Caged (1950).

In his autobiography Cagney by Cagney (1985), the actor said he found the script for White Heat "very formula...the old knock-down-drag-'em-out again, without a touch of imagination or originality." Finding Cody Jarrett to be "just another murderous thug," Cagney said he suggested to the writers to pattern the character of Jarrett and his mother after the legendary outlaws Ma Barker and her boys and to make Cody a psychotic. It has also been said that Cagney improvised some of his dialogue and decided to play Jarrett as a man plagued by blinding migraines (that only his mother could soothe).

In a memo dated May 5, 1941, during pre-production of Yankee Doodle Dandy (1942), James Cagney's brother William (the film's associate producer) and screenwriter Robert Buckner told Warner Brothers producer Hal Wallis that during story conferences they could find no way to sustain the close relationship between the character of George M. Cohan (Cagney's Oscar®-winning role) and his family. Apart from several other reasons, the memo said, "it would be hard to swallow Jimmy Cagney as a guy with a mother or father complex." But Cagney with a mother complex is exactly the key to his performance in White Heat.

By Rob Nixon