The present invention relates to a composition for treating keratin fibers, and in particular human keratin fibers such as the hair, comprising, in a cosmetically acceptable medium, one or more alkanolamines, one or more basic amino acids and one or more additional alkaline agents chosen from aqueous ammonia； ammonium salts of acids whose pKa at 25° C. is greater than 4； alkali metal or alkaline-earth metal hydroxides, carbonates, carbamates and hydrogen carbonates. The present invention also relates to processes for bleaching and/or dyeing keratin fibers, and also to multi-compartment devices or &lsquo；kits&rsquo； for performing these processes.
