The commercial potential of large orbital space platforms or space stations is a key factor that must receive serious attention during the early feasibility and concept study phases. It is recognized that the total development cost will be very great and thus it is essential to identify potential users and their likely investment interest at an early stage. However, the development time of a space platform, say ten years, poses clear problems to both builders and potential users. Some typical problems are mission cost, operational effectiveness, commercial security, ownership and operational responsibility of the platform. Another very important issue is whether the platform should be manned, man-tended or unmanned. All these points are important factors to the commercial potential. The paper will review some of these aspects by using results gained during current studies being made for the European Space Agency. (i) A manned space station is necessary for selected European payloads in material and life sciences. (ii) Manned space station operations need to be complemented by free-flying unmanned platforms for automatic materials processing. (iii) Most payloads identified were for basic research. (iv) Commercial opportunities at this stage were only identified in communications, where the space station is used for orbit staging and assembly. (v) Identification of possible materials-processing payloads will be largely dependent on the flight results obtained from the Space lab mission.