In this Letter, we report the deposition of niobium carbide (NbC) thin films by using a rf magnetron sputtering apparatus with a NbC target. The films were characterized with regard to their structure, chemical bonding states, and composition. It was revealed that cubic NbC films could grow at ambient temperature. The film composition was estimated as a function of deposition parameters. it was found that excess carbon exists within the films deposited at low working argon pressure. This excess carbon seems to be associated with poor crystallinity. Using the present deposition method, oxygen content in the films could be controlled at an extremely low level. Either physical scattering or a chemical etching mechanism was considered to be responsible for the loss of carbon in the film. (C) 2004 American Vacuum Society.