An electronic marketplace supports the interaction among different users to exchange information about products to sell and buy. Significance of electronic marketplaces is given by the huge amount of web sites that are currently available providing services in almost any area one can think of. However, existing similarities among these sites are not precisely documented, which strongly restrains software reuse during the development of new electronic marketplaces. To improve this situation, we propose a domain Platform Independent Model (PIM) that describes both the structural and the behavioural properties of a generic electronic marketplace. Specific application PIMs, which will result in different e-marketplaces, can be obtained from our generic domain PIM by adapting it to each applications requirements. In this way, reuse of our domain PIM contributes to saving cost and time in the development of new electronic marketplaces.