Niobium carbide thin films have been sputter deposited in a reactive argon and methane plasma at substrate temperatures of 700 °C. The background pressure prior to sputtering was typically in the low10−7-Torrrange, the total sputtering pressure was maintained at2×10−3 Torrand the partial pressure ratios of argon and nitrogen were monitored and controlled with a residual gas analyser.Jc–Hcharacteristics were measured by applying a pulsed field and pulsed current method and transition temperatures were determined by recording resistivity versus sample temperature. The structure was studied by x-ray diffraction.Hc2is about 40 kOe and the highestTcis 9.6 K. Several carbide phases and their mixtures were observed and have been correlated to the partial pressure ratios of the plasma.