: The Open Grid Services Architecture (OGSA) provides a high-level framework for service-oriented grid architecture, mostly based on web service standards. The vision of a worldwide computing grid evokes the scenario of electronic markets for grid services. The object of our investigation is a serviceoriented grid architecture model that is compliant with the OGSA specification. We address the problem that the OGSA specification does not meet economic requirements of grid markets explicitly, because it has been designed for other, technical objectives. The problem is investigated from an e-business transaction perspective. The contribution of this paper is a market-centric extension that combines OGSA with market services which meet economic requirements revealed from the investigation perspective.