An in situ plasma processing technique using chemically reactive oxygen plasma to remove hydrocar-bons from superconducting radio frequency cavity surfaces at room temperature has been developed atthe spallation neutron source, at Oak Ridge National Laboratory. To understand better the interactionbetween the plasma and niobium surface, surface studies on small samples were performed. In this arti-cle, we report the results from those surface studies. The results show that plasma processing removeshydrocarbons from top surface and improves the surface work function by 0.5–1.0 eV. Improving thework function of RF surface of cavities can help to improve their operational performance.