We developed gSET as solution for the unsolved problems in the field of dynamic trust management and secure accounting in commercial virtual organizations. gSET establishes trust and privacy between entities in a Grid environment by adapting the concept of Secure Electronic Transactions (SET) used for electronic credit card transfers in eBusiness. Trust is necessary for Grid participants in a business environment. It is also necessary to support the dynamic manner of real markets. As distinguished function, in opposite to existing mechanisms as GSI/CAS/VOMS, gSET allows the user to obtain access to a service without disclosing his credentials to the service provider. This minimizes the service provider’s administrative effort needed for user account management. gSET consists of Grid Services implemented with WSRF/GT4. gSET is an enabling step to make Grids a platform for commercial workflows.