The Oscar given to Orson Welles for his 1941 masterpiece Citizen Kane is expected to fetch up to $1.2 million (£586,000) when it is auctioned later today.
The statuette, awarded to Welles for the best original screenplay of that year, is to go under the hammer along with the personal working copy of the script used by the writer/director.
The 156-page screenplay is likely to go for $120,000 (£59,000) at Sotheby's in New York, it is thought.
Leila Dunbar, senior vice president at Sotheby's, explained the legendary status of the film would provide a huge boost to the asking prices of the Academy Award and script.
"The movie had a star-studded cast," she said.
"Welles was fearless in the filmmaking and he had complete autonomy, all of which helped him create a landmark movie.
"The Citizen Kane script is the most important screenplay of all time," she added.
The Oscar was thought to have been lost until it surfaced at a Sotheby's auction in 1994 after it had been held secretly by a Los Angeles cinematographer who had been given the award by Welles in lieu of payment.
Welles' daughter Beatrice embarked on a lengthy legal battle with the auction house and was eventually given the award, though she was later sued by the academy for attempting to resell it.
But she was permitted to sell the statuette to the charitable Dax Foundation as the award had been given in 1941, nine years before academy rules regarding the resale of Oscars were introduced.