Specialized tools already provide support for creation and execution of parameter sweeps. In such applications many tasks perform similar computations for varying input parameters. So far however none of these existing tools integrates well into service-oriented architectures or allows parametric modeling directly at the service interface. We address exactly this gap and demonstrate practical applicability with a concrete system architecture and implementation. Moreover we extend our services with reduction operators well known from parallel programming that perform certain aggregations or selections over the result set from all tasks of a given parameter study. Our efforts are substantial extensions to previous work on the service synthesis tool the ’Otho Toolkit’ that allows smooth integration of scientific applications into service-oriented Grids. An experimental evaluation concludes our paper.