The present invention relates to a cosmetic composition, preferably for keratin fibers such as compositions for coloring hair, comprising at least these components: a. tris(hydroxymethyl)aminomethane; b. at least one amino acid; c. at least one organic phosphate ester compound selected from: c1. monoester of phosphates of alkoxylated fatty alcohols, wherein the alkoxylated fatty alcohols are composed of C12-C22 fatty alcohols alkoxylated with from 1 to 50 moles of an alkylene oxide, wherein the number of moles of alkylene oxide is with respect to the moles of fatty alcohol; c2. diester of phosphates of non-alkoxylated fatty alcohols, wherein the non-alkoxylated fatty alcohols are composed of C12-C22 fatty alcohols; and c3. mixtures of c1 and c2; d. water; the present invention further refers to a process of manufacturing a dispersion comprising the aforementioned cosmetic composition; a kit of two or more components for coloring keratin fibers; a ready-to-use composition obtainable by mixing the kit components; and a process for coloring keratin fibers comprising said ready-to-use composition.