This paper presents a knowledge based decision support system that can be used to design brushless DC motors. A hybrid approach, that includes an object oriented paradigm using frames and procedural attachments together with a rule based mechanism, is used to build the proposed architecture. The design strategy is implemented using a rule-based successive iterative method, through which the expert designer approach is emulated and embedded in a knowledge-based system. The performance of the proposed system is compared with results from the literature.