Robert Downey, Jr.'s role in the new Spider-Man franchise reboot was a dream come true for the Iron Man star because he used to read the comic books as a child.

The actor reprises his role as Tony Stark and his alter ego Iron Man in Spider-Man: Homecoming, alongside 21-year-old Tom Holland as the titular web-slinger, and it was a job Robert really revelled in.

"I genuinely had a blast," he told breakfast show Good Morning America. "I just love Spider-Man, so to me, being able to participate in reintroducing Spider-Man to a new generation, (was great); that's why it's called Homecoming."

Downey, Jr.'s involvement in the Marvel Cinematic Universe films has been keeping him busy since his 2008 debut as Iron Man, but he recently hinted at plans to hang up his character's famous armoured suit before he's past his prime.

During a recent interview with news.com.au, he said, "I just never want to blow it for the last six or seven (Marvel movies) I have done by dropping the ball because I decided to go do it one more time. I just want to hang up my jersey before it's embarrassing."

The action man expanded on his comments in Wednesday's (05Jul17) pre-taped chat with Good Morning America, explaining he will only retire once he's assured the rest of the Avengers stars can carry on the mantle without him.

"It's like anything with a team," Downey, Jr. shared. "If you're gonna hang up your jersey, you want to make sure that the team is in good shape and they can still compete at a high level, because ultimately that's what made the whole thing (franchise) worth doing anyway."

The star is guaranteed for at least one more outing as Iron Man as he is currently filming Avengers: Infinity War, which is set for release next year (18). It will also feature the return of Chris Evans as Captain America, Scarlett Johansson as Black Widow, and Chris Hemsworth as Thor, alongside Guardian of the Galaxy stars Chris Pratt and Zoe Saldana, Doctor Strange's Benedict Cumberbatch, and new Captain Marvel actress, Brie Larson.