There were a total of 17 episodes, each 8-10 minutes long. The first nine were published under Fleisher Studios, while the next eight were published by Famous Studios. Superman was voiced by Bud Collyer and the animated visuals were closely based on Joe Shuster’s model sheets giving the cartoon a close resemblance to the comic book artwork.
All the episodes are now in the public domain; and here they are collected for your viewing pleasure:
Fleischer Studios Episodes
Ep. 1 – Superman – September 26, 1941
Ep. 2 – The Mechanical Monsters – November 28, 1941