20th Century Fox Home Entertainment, looking to drive up digital sales even at lower margins, has launched an iTunes app offering discounts of up to 70% on a different movie from its catalog for a 24-hour window.

The studio’s Movie of the Day app, available for Apple’s iPhone, iPad and iPod Touch, is launching Wednesday with 2011 release “X-Men: First Class,” available for purchase on digital HD for $6.99 — ordinarily priced at $14.99. The app will offer one of Fox’s recent and classic movies, across all genres, every day for between $4.99 and $9.99. It includes a countdown clock showing how much longer the deal is in effect, to spur purchases.

Among Fox’s approximately 850 movies available on iTunes are “Alien,” “Die Hard,” “Ice Age,” “Planet of the Apes,” “Rio” and “The Sound of Music.” The app is initially launching in the U.S., Canada, the U.K., Australia, Germany and France.

“The Movie of the Day app is a super-convenient way for consumers to access the movies they love at the touch of a button,” said Mary Daily, CMO for 20th Century Fox Home Entertainment. “The app gives movie lovers access to an amazing array of movies every day at a great price.”

The Movie of the Day app provides video clips, summaries, cast and crew information and reviews of each film. Users also can share their purchase via Facebook and Twitter, a feature designed to promote the daily flash sale. The app is powered by storefront-management tools from Premiere Digital Services.