Straightening of keratinous fibers comprises application of a straightening composition containing a polyhydroxy aromatic compound (I) having a pH of =9 on keratinous fibers and raising the temperature of keratinous fibers to 110-250[deg]C, using a heating unit, where the polyhydroxy aromatic compound is not 4,5-diamino-2,6-dihydroxypyrimidine, 2,4-dihydroxypyrimidine-5-carboxylic acid, 2,4-dihydroxy-6-methylpyrimidine, dihydroxyorotic acid or 2,4,5-trihydroxypyrimidine. An independent claim is included for a kit comprising a heating unit having a heating range of 110-250[deg]C and the straightening composition.
