Experiments to separate nickel and chromium were carried out at 298 K on a column packed with porous glass powder (43-74 mu m) using pyridine-2,6-dicarboxylic acid as an eluent. When 0.02 M PDCA eluent was used in the range of pH 1-4, nickel was not adsorbed but was elated with the mobile phase liquid, and the retention volume of chromium was maximum near pH 2. The two metals were isocratically and perfectly separated in the ranges of pH 1.3-1.7 and pH 2.5-3.7. Since the retention volumes of these metals were independent of eluent flow rate in the range of 0.15-3.0 cm(3)/min, the separation time could be shortened by raising the flow rate. Separation was completed in 10 min by using 0.02 M PDCA (pH 1.5) and 13 min by using 0.03 M PDCA (pH 3.0) as an eluent.