The aqueous cadmium sulfide sols (Q-CdS) photoluminiscence activation on Zn2+ and Cd2+ salt introduction was reported. The reversibity of the activation process was tested by dialysis of Q-CdS solutions activated by zinc(II) or cadmium(II) salt additions. The solution pH was monitored over the course of the fluorometric titration, and the hydroxide concentration was observed to steadily decrease consistent with the removal of hydroxide from solution in proportion to the amount of added salt.