A South Australian teenager who went missing in Victoria's high country while on a school camp has been found safe and well.

Tom McMahon, 15, was located in Merrijig near Mount Timbertop on Monday night after a local resident reported seeing him near Mount Buller Road around 8.30pm (AEDT).

Police and family members went to the area and found him. I t's believed Tom, from Medindie, went hiking alone about 4am on Tuesday.