The complexation reactions between methylthymol blue(MTB) and Co2+ ، Ni2+ ، Cu2+ ، Zn2+ and Pb2+ ions have been studied indifferent water-methanol mixtures at pH 4.45 and 25 ـC by a spectro-photometric technique. The stepwise stability constants of the resulting 1:1and 2:1 (metal ion to ligand) complexes were determined from the absor-bance-mole ratio data. It was found that the overall stability constants ofthe complexes formed increase in the order Zn2+
