CrAlSiN nanocomposite coatings with different (Al+Si)/Cr atomic ratios were deposited by a lateral rotating cathode arc technique. Their composition, structural, and mechanical properties were characterized by energy dispersive analysis of X-rays, X-ray diffraction, nanoindentation, and Rockwell indentation experiments. Abrasion resistance of the coatings was evaluated by a micro-scale abrasion tester against a SiC slurry. The hardness of the CrAlSiN coatings increased gradually with increasing (Al+Si)/Cr atomic ratio and a maximum hardness of about 40 GPa was obtained at around (Al+Si)/Cr=1.62. Upon further increasing the (Al+Si)/Cr atomic ratio, the coatings' hardness dropped significantly. The coatings' abrasion resistance was found be proportional to the coatings' hardness. In comparison with TiAlN, the CrAlSiN coatings showed a higher abrasion resistance, particularly for coatings with a hardness higher than 30 GPa. Selected CrAlSiN coatings with the highest hardness were deposited on WC-based end-mills. An evident improvement in the performance of the CrAlSiN-coated end-mills was observed compared to the TiAlN-coated ones for cutting a hardened tool steel under high speed dry machining conditions. (C) 2010 Elsevier B.V. All rights reserved.