A process of straightening the hair comprising the following consecutive steps: i) applying to dry hair a hair treatment composition having a pH of 3 or less at 20° C. and comprising at least 4 wt % of the total composition of a bidentate or tridentate carboxylic acid ii) leaving the product o the hair for at least 5 minutes iii) rinsing the product from the hair and iv) combing.
