In this study, the mechanical behavior of r.f. magnetron sputtered indium tin oxide (ITO) films with glass and polycarbonate as substrates was investigated. The microhardness, pull-off strength and scratch adhesion strength were measured to assess the film properties. The ITO coating improves the hardness of the polycarbonate substrate. Incorporation of oxygen in the sputtering ambient enhances the crystallization of the film; consequently, the film hardness of coated polycarbonate and the scratch adhesion strength of coated glass are improved. The thermal expansion mismatch between ITO and polycarbonate results in poor adhesion when polycarbonate is employed as the substrate.