The hydrolytic polymerization of chromium (Ⅲ) ion was investigated in the concentration rango of 0.0025M~0.0002M, The compositions of various hydrolysis products obtained by means of "average composition" method showed that trinualear species are predominant and that the number of OH- bound to each ohromiumion increased when the concentration of the ion decreased or/and the pH increased. The hydrolysis constants of the ions of the same degree of polymerization abtained at different concentrations were found to be very consistent with each other, and the β₄₃ is in agreement with that obtained in Part Ⅰ of this series of studies. Tho composition presented in this paper is also consistent with the charges on the polynualear nations as determined by means of the coagulation value mothod.