This paper comparatively studies the tribological behaviour of different types of diamond-like carbon (DLC) coatings in a reciprocating sliding wear test. The results are interpreted in terms of structure and surface morphological characteristics. At the beginning of each reciprocating sliding wear test, the higher coefficient of friction of the DLC coatings reflects the original surface conditions of contacting counterfaces, whereas the low coefficient of friction achieved under the steady regime is linked to the presence of wear debris and an enlarged real contact area. sp(2) carbon bonding has been related to the occurrence of a higher coefficient of friction and surface damage of DLC materials compared to bulk diamond. The a-C coatings and ta-C films have a lower coefficient of friction at the steady regime than the a-C:H coatings, possibly due to a significant amount of hydrogen in the a-C:H coatings. (C) 1998 Elsevier Science S.A.