Mobile devices are able to spontaneously form highly dynamic ad hoc networks allowing for communication even when no infrastructure exists. Ideally, these networks enable the participating devices to share resources and services, thus overcoming the often severe limitations of the individual devices? capabilities. In order to make this possible, powerful semantic service trading is needed. In this paper, we propose a semantic overlay of hierarchical service rings to achieve this goal. In contrast to existing approaches this method is adapted to the specific characteristics of ad hoc networks.