The film's score was written by composer Patrick Doyle, a frequent collaborator of Branagh. Doyle described Thor as "the most commercially high profile film I have done since Frankenstein",[117] adding that the composing process had the challenge of trying to find a tone that fit the duality of Asgard and Earth. Thus Doyle and Branagh had frequent discussions on the musical direction,[118] with the director suggesting a contemporary feel and having a balance between the music and "grand images [that] were not in any way hyperbolized", and the composer in turn implementing "a strong sense of melody, which he responds to in my work". As Doyle declared that his own Celtic background made him familiar with Norse mythology, an old Celtic folk song also provided the inspiration for Thor's leitmotif.[117] A soundtrack album was released by Buena Vista Records in April 2011.[119]
The film also features a song by the Foo Fighters, "Walk", in both a scene where a powerless Thor shares some boilermakers with Selvig in a roadhouse, and the film's closing credits. Marvel president Kevin Feige stated that "Walk" was a last minute addition, that the crew felt had "these eerie appropriate lyrics and themes" upon hearing it. Branagh in particular thought that "these lyrics about learning to walk again" were appropriate "of [a] movie about redemption, learning to be a hero."[120]
