A nine-year-old boy with cystic fibrosis had his dream come true when he became a superhero for a day in Australia.

As Iron Boy, Domenic Pace captured henchmen and was engaged in a fierce battle with evil Ultron who attacked his native Sydney.

But for Domenic, there was never any real danger - as it was part of a community project by the Make-A-Wish Foundation and New South Wales Police.

The youngster was put to work by NSW Police Commissioner Andrew Scipione who called Sydney’s own ‘Iron Boy’ to help keep residents safe.

Domenic donned Iron Boy's superhero costume and pledged to "defeat Ultron once and for all".

With live news updates, fans across the world were able to follow Iron Boy's adventures - including a special shout out from the real Iron Man, Robert Downey Jr.

Domenic, diagnosed with from the life-threatening illness, Cystic Fibrosis, has always dreamed of becoming a famous superhero.

"From a young age he would only answer to Tony [Tony Stark is Iron Man]," his mother said.

"He was a very caring child, more interested in helping children and other people than playing toys. He always wanted to know what was going on around him in the world and how he could help others."