"Chemistry" received positive reviews from music critics. Talia Kraines of "BBC Music" decided that the album was "quirky, modern and dripping with attitude" and "holds no disappointments." Virgin Media gave the album five stars, saying it was "bursting [...] with invention, quirky lyrics, tongue-in-cheek sauciness and [...] appeals to grown-up pop fans and music critics as well as to the teenyboppers." Yahoo! Music concurred by declaring that "Chemistry" was "as devilish and quirky and downright uplifting as anything else released by anyone this year." "The Guardian" was extremely positive in its review, saying it "spends 45 minutes doing the last thing you expect it to." "The New York Times" referred to the album as "endlessly entertaining". In comparison to Girls Aloud's previous albums, Entertainment.ie referred to "Chemistry" as their "best offering yet [...] overflowing with pop hooks, sassy production and choruses just waiting to take up permanent residence in your head." "The Daily Telegraph" said that Girls Aloud have "simply got much, much better [...] albums will have to get better in order to survive. It's happened here. Judging by Chemistry, Girls Aloud's songwriters are now working as hard as the band are." MusicOMH said it "achieves the almost impossible in bettering its predecessor." Dom Passantino of Stylus Magazine said he did prefer "What Will the Neighbours Say?", but gave "Chemistry" an A-.