A compound solid lubricating film containing a MoS 2 top layer deposited on DLC interlayer by UBM sputtering technique was investigated for its tribological applications in humid environments. TEM, Raman and XRD analysis revealed the amorphous nature of the MoS 2 film which contains only short-range order in its lattice structure. The as-deposited MoS 2 compound films showed well-bonded interfaces. The MoS 2 , however, is very susceptible to humidity and oxidation, which resulted in higher friction coefficients and lower wear life. A friction coefficient of 0.05 was measured between steel balls and MoS 2 in atmosphere of 90% RH. Excessive abrasive wear was identified, as a result of the wear debris and the oxidized transfer layers between MoS 2 and its counterpart. The inclusion of a supportive DLC interlayer has effectively improved the wear behavior of MoS 2 films under various loading conditions. The overall wear mechanism of MoS 2 was complicated due to its oxidation problem which needs to be resolved for successful usage of MoS 2 in humid environments.