Orson Welles' 1941 Oscar for "Citizen Kane," considered one of the greatest movies of all time, will go on the auction block in December.

The Academy Award for Best Screenplay is estimated to sell for between $800,000 and $1.2 million, Sotheby's auction house said Tuesday.

It is the only Oscar Welles ever won.

The golden statuette, believed to have been once lost by Welles himself, resurfaced in 1994, and after an extended legal battle was returned to his estate.

In 2003, it was acquired by the Dax Foundation, a Los Angeles-based charity. The proceeds will help fund the organization's worldwide efforts.

"Citizen Kane," a story about a power hungry publishing magnate played by Welles and "widely believed to be based on the life of William Randolph Hearst, was voted the number one film in history by the American Film Institute in 2007 and by the British Film Institute in 2002.

The Oscar will be sold Dec. 11 and displayed at Sotheby's in New York on Dec. 7-10.