The present invention relates to a process for permanent shaping and dyeing carried out one after another with compositions providing improved and milder shaping and dyeing of hair, especially human hair. The inventors of the present invention have unexpectedly found out that when commonly used permanent shaping and dyeing compositions are mixed with another composition comprising predominantly carboxylic acids, the permanent shaping and dyeing effects of the compositions are improved, homogeneous permanent shaping and dyeing of hair fibers is achieved and natural cosmetic properties of hair are maintained.
