In recent years, grinding techniques for precision machining of brittle materials used in electric, optical and die parts have been improved by using superabrasive wheels and precision grinding machines. The completion of optimum dressing of superabrasive wheels makes possible the effective precision grinding of brittle materials, but the present dressing system cannot provide sufficient control for optimum dressing of the wheels. In this study, a new and grinding technique of optimum in-process electrolytic dressing is proposed. This system can carry out optimum in-process dressing of superabrasive wheels, and give very effective control according to unstable current and gap increase. Therefore, the optimum in-process electrolytic dressing is a good method to efficiently obtain and mirror-like grind brittle materials. (C) 1997 Elsevier Science Ltd.