Thin films of TiCrAlSiN were deposited on SKD 11 toot steel substrate using TiCr and AN cathodes by a cathodic arc plasma deposition system. The influence of nitrogen pressure, AlSi cathode arc current and bias voltage on the mechanical and structural properties of the films were investigated. The hardness of the films increased with the increase of the nitrogen pressure from 0.4 Pa to 4 Pa. A further increase in pressure decreased the film hardness. The hardness of the films increased as the AN cathode arc current was raised from 40 A to 45 A, and then decreased with further increase of the current. The film hardness increased rapidly from 0 V to - 100 V. It then leveled off with a further increase of the bias voltage. The films exhibited a maximum hardness of 43 GPa. (C) 2008 Elsevier B.V. All rights reserved.