The invention relates to dimethoxy docetaxel acetone solvate or (2R,3S)-3-tert-butoxycarbonylamino-2-hydroxy-3-phenyl-propionate of 4-acetoxy-2 alpha -benzoyloxy-5<,20-epoxy-l-hydroxy-7 beta ,10 beta -dimethoxy-9-oxo-tax-ll-ene-13 alpha -yl and to the preparation thereof by crystallisation from a hydro-acetone solution.