The Grid has revolutionized the way computations are done on the Internet. Access to remote computational resources and ad hoc creation of virtual organizations across administrative domains opens new opportunities on the Grid. The newly developed web services based Open Grid Services Architecture makes the Grid more accessible by allowing the Grid to be constructed from distinct platform independent components. Together they provide an environment for application sharing (or trading), collaborations and access to remote data repositories. The application marketplace is a natural extension to this application sharing environment. The marketplace addresses the fact that the existing infrastructure is still incomplete without provisions for publishing and discovering applications and resources, including the application descriptors that must be moved between the market participants. This work demonstrates a web service instance-based infrastructure, the application market that allows the sellers, the application and the CPU providers to publish their applications for the users to find and use. The application market uses a portal architecture built on top of Globus toolkit 3.0 that interacts with the providers and the users. The market services provide distinct interfaces that allow providers to advertise applications and users to select, configure, and run these applications. The applications themselves are modeled as stateful objects represented using XML which can be exchanged between the providers and users when required. The marketplace, through its interfaces, effectively hides the compute resource and application complexity thus allowing end users to explore and use applications unfamiliar to them with ease.