Holy Kryptonite! Superman returns – without his pants

For more than 70 years he has flown to the world's rescue dressed in a trademark red cape, blue suit and startling tight red trunks worn outside his trousers. Superman, however, is about to lose his pants.

DC Comics, creators of the iconic superhero, are rebooting the Man of Steel franchise as part of an overhaul of their comic book empire, which will see all their titles starting again at issue No 1.

The move promises significant changes for DC's superhero family – which includes Batman, Wonder Woman and the Green Lantern – with new characters, stories and, crucially, costumes in 52 new first editions, due out in September.

The Scottish writer Grant Morrison and artist Ralph "Rags" Morales will launch the series once again with a new first edition of Action Comics, the 21st-century version, part of a huge initiative to a reach a new audience. The most controversial style adjustment revealed on the cover of the "first edition", due out in August, is the surprise scrapping of the red trunks that Superman has worn since he first appeared in June 1938.

But fans will be reassured to know that the Man of Steel will keep his red cape and blue bodysuit and, seeing as the pants were always worn on the outside, his modesty should remain intact.

Superman, as he appears in the comics, has undergone several style tweaks over the course of 901 editions. He even sported a mullet haircut for a brief spell in the 1990s. The franchise has also spawned a litany of spin-offs such as Supergirl and Superboy, both of whom will be getting new first editions.

Jim Lee, DC artist and co-publisher, promised that the new stories would tackle real-world, modern-day events and pledged more diversity, with bigger roles for black, Hispanic and gay superheroes, including Batwing, billed as "the Batman of Africa".

However, critics claim that despite the revamp, the move is little more than a gimmick to boost flagging sales. Aficionados point out that the first edition of any comic book is guaranteed to become a collectors' favourite and DC will cash in on fan's anxiety to own a copy of one of the new "first" issues.

Comic books have struggled to attract new readers in recent years, with superhero films and video games proving far more popular than the printed stories that first inspired them. For the first time, the new comics will be available online and on smart phones.

"We're trying to move not just the company but our industry to new areas and new audiences. This isn't about turning around a single character or telling a new story. What we're trying to accomplish is to widen the breadth of our stories and the appeal of characters, and go after different distribution systems," Dan DiDio, a co-publisher of DC Comics, said.

A second picture of the new Superman released last week suggested an even more drastic fashion departure: a T-shirt, jeans and heavy work boots. However, it is believed that this is not a permanent change. Even superheroes like to dress down on occasions.