MoS 2 coatings were deposited by ion-beam-assisted deposition (IBAD) with and without a 30 nm TiN interlayer on Ti, Ti-6Al-4V, and steel substrates and slid in dry air against Ti-6Al-4V and steel under two different contact conditions. In the constant load condition, the friction coefficients for coated Ti alloys sliding against Ti ranged from 0.02 to 0.06, while endurance ranged from 30 to 625 krev. The tribological behavior was independent of TIN interlayer and was similar to that for MoS 2 -coated steel sliding against steel. Shear strength parameters S0 and α of IBAD MoS 2 were measured on Ti-6Al-4V by varying the mean hertzian pressure, 0.28 GPa P H 1.3 GPa; S 0 ranged from 12 to 19 MPa and α ranged from 0.005 to 0.021, similar to sputter-deposited MoS 2 on steel. At P H =1.3 GPa, the Ti alloy was loaded beyond its elastic limit, but the 300 nm thick IBAD MoS 2 was able to protect the substrate by maintaining integrity and lubricity.