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The aim of the presented research work is to investigate the effect of different surface preparation - glass bead blasting (GBB) and polishing (P) on the friction behaviour of the duplex treated Diamond-Like Carbon (DLC) coated X42Cr13 Plastic Mold Tool Steel. Duplex treatment involved plasma nitriding followed by Plasma Enhanced Chemical Vapour Deposition (PECVD) and the surface preparation was accomplished after the nitriding prior to PECVD coating. The friction behaviour was studied using ball-on-disc wear test defining the friction coefficient vs. sliding distance curves, the morphology of the wear tracks was investigated by optical microscope. Based on the presented experimental results it is established that GBB and polishing procedures have measurably different influence on the frictional and wear behaviour of the superhard upper layer, resulting in lower value of friction coefficient, less wear debris and better adhesion of the coating to the substrate in case of GBB operation. In addition, some test results are presented for uncoated, simply nitrided samples to emphasize the advantage of duplex treatment on the wear/friction behaviour the investigated tool material.