Co-sputtered thin films of MoSx with Au have been deposited in order to investigate the relationships between tribological behavior and film microstructure. The mechanical properties of the composite films were investigated by pin-on-disk wear testing in 50% relative humidity air as a function of Au concentration. X-ray diffraction measurements indicate that the microstructure is strongly affected by the inclusion of Au and that there is a strong correlation between microstructure and tribological performance.