Based on the story, "The Electric Man" which Universal had purchased for $3,300 in 1935 as a potential Boris Karloff / Bela Lugosi vehicle to be titled "The Man in the Cab." The studio, in the midst of a financial debacle at the time, shelved the project for over five years, assigning the re-write to George Waggner (working as "Joseph West") who re-tooled it as "The Human Robot."
The trivia items below may give away important plot points.
Lionel Atwill plays a mad scientist here and in The Ghost of Frankenstein (1942). In both films Lon Chaney Jr. plays the monster and kills each of Atwill's respective characters the same way, with electricity. The one other title featuring Atwill as a mad scientist was the 1942 release "The Mad Doctor of Market Street."