Solid modeling of objects forms an important task in design and manufacturing. Recent developments in the field of layered manufacturing have shown potential for the physical realization of heterogeneous (multi-material) objects. Thus, there is a need to represent material information as an integral part of the CAD model data. Information models for the representation of product data are being developed as an international standard called STEP (ISO 10303). However, the current application protocols focus on the representation of homogeneous objects only. This paper proposes an information model to represent heterogeneous objects using the information modeling methodology developed for ISO 10303. This will help in providing a uniform base in the development of heterogeneous solid modeling systems. It will also equip the solid modeler with the ability to integrate with other applications and process planning in the domain of layered manufacturing.