A method of straightening the hair comprising the step of applying to the hair a hair treatment composition comprising: i) at least 0.4 wt % of the total composition of a sugar alcohol； and ii) at least 0.4 wt % of the total composition of a bi or tridentate carboxylic acid in which the ratio of sugar alcohol to acid is 1:5 to 5:1； and iii) heating the resulting composition to a temperature of greater than 120° C. for at least 10 seconds.
