Firefighters were called to the Greta South property shortly before 10am and flames had fully engulfed the house.
It took firefighters from Greta, Myrrhee, Moyhu and Glenrowan about 40 minutes to control the blaze, which had totally destroyed the Jones Lane house.
District 23 Operations Manager Stewart Kreltszheim said they believed the fire started when a gas light was left unattended.
“The property had no electricity and the generator had failed so the occupant lit a gas light. Unfortunately he fell asleep and woke up when the fire had started,” he said.
“It’s a timely reminder to residents - never leave naked flames unattended.”
A male occupant suffering burns and shock was treated on scene by a nurse before being taken to hospital.
Firefighters remained on scene until about 1pm blacking out.