According to Variety magazine, Paltrow will join Robert Downey Jr. and Terrence Howard in the production. The feature film will be directed by filmmaker John Favreau and distributed by Paramount Pictures, and is expected to be released on May 2, 2008.
Paltrow, 34, will play Virginia "Pepper" Otts, the personal assistant to an industrialist who builds a suit of armour and fights crime.
Filming for Iron Man is set to begin in March in Los Angeles.