The present invention is on a cosmetic composition for improving color brilliance and wash fastness of artificially-colored keratin fibers. The effect is achieved by the combination of pyrrolidone carboxylic acid esters, pyrrolidone carboxylic acid and/or its salts, and amodimethicone microemulsion. A process for treating keratin fibers, a use of the composition and well as a kit-of-parts is disclosed.
