Screenwriter Mark Protosevich has developed a script for a live-action Thor film. In December 2007, he described his plans for it "to be like a superhero origin story, but not one about a human gaining super powers, but of a god realizing his true potential. It's the story of an Old Testament god who becomes a New Testament god". In September 2008, Kenneth Branagh was brought on board to direct the film. He described it as "a human story right in the center of a big epic scenario."

In March 2009, Marvel Studios moved the release date of Thor from July 16, 2010 to June 17, 2011, moving the film back a year. Days later, Thor's release date was moved again to May 20, 2011, where it currently stands.

Also in March 2009, Deadline Hollywood Daily reported that Natalie Portman could earn a role in the film starting several casting rumors. Official casting news began when Deadline Hollywood Daily reported Chris Hemsworth was cast as Thor in May 2009 with Tom Hiddleston being added as Loki a couple days later. Natalie Portman was officialy cast as Jane Foster in June 2009.

Kenneth Branagh revealed plans to start production in January 2010 and Kevin Feige stated that Thor will be present at Comic-Con 2010. It was also revealed that Thor's production schedule would begin in January 2010 and continue through April. The Warriors Three were cast in November 2009 with Stuart Townsend (Fandral), Ray Stevenson (Volstagg), and Tadanobu Asano (Hogun). A complete cast and crew list can be found here.

On January 7, 2010, Thor moved its release date up two weeks to fill the May 6, 2011 spot vacated by Spider-Man 4 due to script delays. Thor started production on January 8th with plans to film through April.