An Australian boy, who has non-verbal autism, has been found safe and well after going missing while hiking in the Victorian bush two days ago.

14-year-old William Callaghan became separated from his family as they neared the summit of Mount Disappointment on Monday and had been without water or food in freezing conditions when he was discovered on Wednesday.

Following a two-day search involving over 400 volunteers he was rescued by local bushman, Ben Gibbs, who had grown up in the area and told reporters he knew the mountains well.

“I was just wandering through the bush, it was quite thick so I was breaking my way through it,” Gibbs told Nine news.

“He was just about 15 metres from me just standing there, just really angelic. 

"I heard that he liked Thomas the Tank [Engine] so I just talked to him about Diesel and Bertie and stuff like that … just to calm him down.”

Gibbs offered Will a pair of socks as well as chocolate, water and a coat before the emergency services arrived to transport them back to the volunteer camp.

William’s mother Penny Callaghan told reporters she was ’really overwhelmed’ to have him back.

She added that ’under the circumstances, he is quite calm’ and continued by thanking the volunteers.

“More than anything, thank you everyone,” she said.

"I’m so grateful, you’re all amazing. What an amazing community,” she said.

She then added that his first request was for a McDonald’s.

Paramedics treated him for an hour at the camp and he was then taken to hospital for observation.