The band's debut album The Big Come Up had been tremendously successful for an independent rock band and Thickfreakness further increased their profile. It continues The Black Keys' tradition of raw, heavy blues-influenced garage rock. Thickfreakness is known in Japan as Inazuma Rockin' Blues, with "inazuma" meaning "flash of lightning".
Songs such as "Set You Free" won the pair some mainstream success as being featured in the soundtrack of the 2003 film School of Rock. Heavy comparisons to another American blues-influenced garage rock duo, The White Stripes, were often made by the music media.
Most of the album was recorded in December 2002 during a single 14-hour session in Patrick Carney's basement using an early 1980s Tascam 388 8-track recorder. This approach was necessary because the group spent its small advance payment from Fat Possum Records on rent. The liner notes claim this is Carney's "patented recording technique called 'medium fidelity'". The result is an older sounding sound. The song "Midnight in Her Eyes" is one of the few Black Keys songs that used a bass guitar; Dan Auerbach dubbed a bassline by playing a Guild SG-style bass through a guitar amp into the song. Part of "Set You Free" was recorded by Jeff Saltzman.
Thickfreakness was The Black Key's first breakthrough album, it established them as an indie-rock blues band. Their recognition from Thickfreakness led them on a rigorous tour schedule including opening for singer/songwriter Beck [on his "Sea Change" summer tour] in the summer of 2003.  This genre of music was already gaining in popularity [see The White Stripes] but their particular style was something never heard before. According to critics, "Thickfreakness is an album that's meant to be felt as much as heard, rigged with plunging riffs, Auerbach's charcoal-smoke singing voice, and rhythmic pockets as deep as quicksand".  It was during this time that Auerbach began writing material for their next album. When the two returned from touring, Auerbach's landlord had sold his house where the duo wrote Thickfreakness in the basement. They found an abandoned tire factory in their hometown of Akron which was where they wrote their next album "Rubber Factory" named after the factory in which the album was conceived. The duo had to postpone a tour in Europe that summer due to exhaustion. The album placed in the top ten spot in the final ten albums for the Shortlist Prize in the summer of 2003. Black Keys perform in front of a sold out audience at Madison Square Garden in 2012.
^Perry, Jonathan (2003-05-16). "BLUES CRUSH THE BLACK KEYS CREATE GRITTY, BLUESY ROCK THAT SOUNDS AS IF IT ROLLS DOWN FROM THE HILLS BUT ACTUALLY COMES RIGHT FROM THE SUBURBS BLACK KEYS GET DOWN AND DIRTY WITH THE BLUES". Boston Globe.|accessdate= requires |url= (help)