He's one of the world's most famous artists, but no Australian public gallery has ever owned a painting by Salvador Dali – until now. Almost.

The National Gallery of Victoria has put a $4 million downpayment on a rare painting by the mustachioed surrealist, which had been hidden away in private collections since the mid-1960s.

NGV director Tony Ellwood, left, and senior curator international art Ted Gott, with the Dali painting. Credit:Joe Armao

And, despite a recent bump in income from private donors, government funding bodies and exhibition ticket sales from record visitor numbers, the gallery is asking Victorians to reach into their own pockets to make up the $1.5 million shortfall owed to the private seller.

"It's not that we have to ask the public to help us," said NGV senior curator international art Ted Gott, who curated the gallery’s 2009 Dali retrospective, Liquid Desire.