The present invention relates to a process for straightening or relaxing hair comprising:(a) pre-alkalizing the hair by contacting it with an alkaline composition having a pH of from 8.0 to 10.5 to form pre-alkalized hair(b) applying onto the pre-alkalized hair a hair straightening/relaxing composition containing:(i) from 0.1% to 50% by weight of at least one weak non-hydroxide base and(ii) remainder, to 100%, a cosmetically acceptable mediumto form treated hair, and(c) smoothing the hair using a combination of heat and means for physically smoothing hair the smoothing step (c) being performed prior to and/or after the application step (b) of the hair straightening/relaxing composition.
