This book constitutes the refereed proceedings of the 6th International Conference on Electronic Commerce and Web Technologies, EC-Web 2005, held in Copenhagen, Denmark in August 2005.

The 39 revised full papers presented were carefully reviewed and selected from 139 submissions. The papers are organized in topical sections on ontologies, process modelling, and quality of data in e-commerce, recommender systems, e-negotiation and agent mediated systems, business process/strategic issues and knowledge discovery, applications, case studies, and performance issues in e-commerce, Web usage mining, e-payment approaches, security and trust in e-commerce, and web services computing.