Cu2S films on the copper substrate are successfully prepared through the in-situ hydrothermal reaction between sulfur powder and copper foil. The morphological and chemical structures of films were investigated by using scanning electron microscopy and X-ray photoelectron spectroscopy. The friction-reducing performance of Cu2S film obtained was evaluated in dry sliding contact with steel ball. It is observed that as-obtained Cu2S films have the water contact angle as high as 140 degrees without any chemical modification, possessing low friction with extremely long duration. (C) 2012 Elsevier B.V. All rights reserved.