The ICETAS initiative from ESA aims to provide the European space community with: A framework for development and integration of software tools supporting the thermal design, analysis and verification process for space applications. Effective exchange of thermal analysis models and data. In phase 2 of ICETAS a consistent set of user requirements was formulated, derived from so-called Use Cases. The Use Cases give step-by-step descriptions of the interaction between the thermal engineer and the software system. ICETAS covers the thermal engineering process all the way from requirements analysis and conceptual design to test evaluation and flight support.The user requirements activity was followed by the definition of a complete, object-oriented information model (the Common Data Structure - CDS) capturing all data entities and associations needed in the discipline. The CDS was defined as a STEP/EXPRESS schema and the STEP physical file format was tentatively selected for exchange of models and data.The practical feasibility of the approach was investigated through the development of a prototype implementing a subset of ICETAS in the C++ language on top of a commercial Object Oriented Database Management System (ONTOS). This prototype development gave very promising results.