This paper presents an optimal control method for DCDC converters. The system is modeled as a mixed logical dynamical system so that the switching property can be considered explicitly. Specifically, the input of the system is confined to a discrete value whereas the output to be controlled is a continuous value. The optimal control law for the system is obtained by means of off-line model predictive control. The effectiveness of the proposed method is illustrated through numerical simulations and experiments. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.