Chromium chloride (CrCl3) or chromium sulfate(Cr-2(SO4)(3)) content increased trivalent chrome deposition rate. The addition of formic acid and the relative content change of potassium hydroxide decreased the trivalent chrome deposition rate. Industrially applicable trivalent chromium layers with more than 200 mu m thick were well prepared at the conditions of pH with the range of 1.3-1.8, electrical current density of 5.0-5.6 A/cm(2) and applied voltage of 4.0-5.9V. Average microhardnesses of the chromium layers prepared in the chromium chloride and chromium sulfate solutions are about 803-820 and 700-712 Hv, respectivevly. The wear resistance of the trivalent chromium layers was improved by plating voltage which was related to residual compressive stress on the chomium layer.