A purportedly pristine copy of the first Superman comic book could fetch millions of dollars when it goes up, up and away in an auction at online marketplace eBay.

A copy of Action Comics #1 in which the Kryptonian superhero made his debut in 1938 will be offered in an eBay auction that opens on August 14 and run for ten days.

"This is an extraordinary opportunity to acquire the most valuable comic book in existence and we look forward to sharing a piece of pop culture history with the global eBay community of 149 million buyers," Gene Cook of eBay marketplaces said in a release.

The issue being put on the Internet auction block by collectibles dealer Darren Adams was touted as the "Holy Grail" of comic books and one of as few as 50 unrestored copies in existence.

Another copy of the same issue with an equally high rating from grading service Certified Guaranty Company (CGC) sold for more than two million dollars three years ago.

"The book looks and feels like it just came off the newsstand," CGC primary grader Paul Litch said in a release.