Liquid-liquid partition coefficients (KD) of both Cr(III) and Pd(II) complexes of several β-dlketones between dodecane and a water-methanol mixture have been determined by a combined method of batch technique and high performance liquid chromatography (HPLC). The KDof each metal complex is enhanced as the methanol content of the mixed liquid phase decreases. In bothhomologs of the Cr(III) complexes and the Pd(II) complexes, KDincreases with an increase in the molecular size of the complex, although Cr(III) complex tends to have smaller KDthan the Pd(II) complex whose molecular size is comparable with that of the Cr complex.