Namatjira painting from 1937 found in SA

An early painting from the first Aboriginal artist to paint in the western style - Albert Namatjira - has been found hidden in a home in Adelaide.

The 1937 painting of the Hermannsburg Mission, in the Northern Territory near Alice Springs, could fetch up to $18,000 when it goes to auction on Sunday after being found in a deceased man's home.

"The unique thing about this little picture is that it's painted on beamwood and it's the first painting of the Hermannsburg Mission," Elder Fine Art antique auctioneer Jim Elder told ABC radio on Wednesday.

Mr Namatjira, an Arrernte man from Central Australia, created about 2000 artworks during his life and died aged 57 in 1959.

He's best known for his watercolour paintings of the outback.

Mr Elder said he was incredibly pleased that the people who discovered the 79-year-old artwork came forward to get it valued rather than throwing it out.

"We lose so many historical items in this manner. It's just the shipwreck of time. They [people] may not know anything about art," he said.