A method for dyeing hair is disclosed. The method comprises (1) treating hair with an oxidative colorant agent (A); (2) subsequent to (1), treating the hair with a CH-acidic hair dyeing agent (B); and (3) subsequent to (2), treating the hair with a cosmetic decolorizing agent (Ox). The method comprises a time interval between (1) and (2) of from about 1 minute to about 1.5 months, and a time interval between (2) and (3) of from about 1 minute to about 1.5 months. A process for multitonal dyeing of hair is also disclosed. The process comprises preparing an oxidative colorant agent (A); treating hair with the agent (A) to give a colored hair; preparing a CH-acidic hair dyeing agent (B); treating the colored hair with the agent (B) to give a dyed hair; and treating the dyed hair with a cosmetic decolorizing agent (Ox) to give a multitonal dyed hair.