The objective of this paper is to report on the development of a Computer Aided Conceptual Design (CACD) Tool for the Design of Complex Electromechanical Systems (CEMS). Few methods and tools exist for supporting the conceptual design stage; this is a paradox considering that decisions at this stage have the greatest influence in the cost and characteristics of the final product. Two main issues were identified: Standardization and Compatibility. The first refers to the variety of ontologies (such as functions and behaviors) proposed by several authors. These ontologies may work on their own, but they don’t "talk" to each other. Even if this issue is solved, there is no compatibility between elements from different tasks (e.g. function to behavior). The proposed approach solves these two issues without sacrificing generality.