The actress has since called her co-star Robert Downey Jr. a "wimp" for complaining so much about having to wear the hot and uncomfortable costume in three films.
Paltrow admits she was wary of putting on the suit, but she was surprised when it wasn't as bad as she thought it would be.
She told Graham Norton: "I get to wear the Iron Man suit for a while - it's very cool... It's quite cumbersome but not so bad. I thought it was going to be terrible because in the first two movies Robert would put on the suit and start sweating, he'd have a nervous breakdown and would meditate and cry. He was in hell.
"So, I was like, 'Wow, I'd better start mentally preparing myself for the suit,' and I put it on and was like, 'This guy is a wimp, it's really not that bad.'"
In the third installment of the massively popular franchise, Tony Stark's personal world is destroyed and he embarks on a harrowing quest to find those responsible. With his back against the wall, Stark is left to survive by his own devices, relying on his ingenuity and instincts to protect those closest to him. "Iron Man 3" hits theaters May 3.