It happened at a pole barn just south of Vincennes. Firefighters got the call just before 10:15 this morning.
Authorities have said the man who died was in his 50's. His name has not been released.
The Indiana State Fire Marshall's Office and the Vincennes Township Fire Department are investigating the cause.
The Knox County coroner says the victim is 50-year-old Daniel Toth.
He died of smoke inhalation.