This book constitutes the refereed proceedings of the 9th International Conference on Electronic Commerce and Web Technologies, EC-Web 2008, held in Turin, Italy, in September, 2008 in conjunction with Dexa 2008. The 12 revised full papers presented together with 2 invited papers were carefully reviewed and selected from numerous submissions. The papers are organized in five topical sessions on security in e-commerce, social aspects of e-commerce, business process and EC infrastructures, recommender systems and e-negotiations, and Web marketing and user profiling.