Disclosed are methods and compositions for altering the color of hair, comprising treating the hair with a pre-alkalizing composition and then treating the hair with a color-altering composition comprising at least one first oxidizing agent chosen from peroxides, persulfates, perborates, percarbonates, peracids, bromates, their salts and mixtures thereof, and further optionally comprising at least one fatty substance and/or thickening agent, and/or at least one second oxidizing agent. The methods may further optionally comprise applying onto the hair a coloring composition comprising, in a cosmetically acceptable carrier, at least one dye compound chosen from oxidative dye precursors, and direct dye compounds.
