A fatty phase for the preparation of hair dyes, consisting of a semi-finished product containing the proportions of stearyl and cetyl alcohols suitable for the preparation of the dye. In relation to the prior art, the invention allows a semi-finished product for preparation of hair dyes to be obtained, consisting of a fatty phase with the ingredients already measured out and mixed, so as to be ready to be integrated, inside the mixer, with the remaining components (colorants, etc.) that make up the final formulation of the dye.