We have developed the ZENTURIO experiment management system for performance studies, parameter studies, and software testing of parallel applications on cluster and Grid architectures. In this paper we describe the design and implementation of ZENTURIO as a Web service-based distributed architecture. We highlight limitations of Web services for deployment on the Grid and propose solutions. Experiment Generator and Experiment Executor services are used to generate, respectively submit and manage experiments on remote Grid sites. A UDDI-based Service Repository publishes information about existing Web service implementations. Factory and Registry services are employed to create and register Web services on the Grid. A GMAcompliant event infrastructure supports high-level notifications about important events. We compare our design with the Open Grid Service Architecture (OGSA) and highlight similarities and differences. We report results of using ZENTURIO to conduct performance analysis...