Interoperability has become one of the big problems of e-commerce since it was born. A number of B2B standards like ebXML, UDDI, RosettaNet, xCBL, etc. emerged recently to solve the interoperability problem. Currently, there exists many B2B standards each provide competing and complementary solutions to B2B interoperability. So, there is a need for serving implementation of these standards from a single, central store to ease the use and management of the implementations. This paper presents EIOP, an E-commerce Interoperability Platform. EIOP is designed to provide a central store for implementations of e-commerce specifications to be able to use and configure these implementations from a single, central point. It defines the term EIOP Component which corresponds to plug&play e-commerce applications that are stored in the EIOP. Categories and Subject Descriptors: K.4.4 [Computers and Society]: Electronic Commerce General Terms: Standardization