The electrical contact resistance and the coefficient of friction behavior of a Cu-DLC nanocomposite coating deposited on a flat brass substrate with a brass ball combination were investigated. The electrical contact resistance decreased by two orders of magnitude over the initial value in around 600 reciprocating cycles and reached 1.5 to 2 milliohms. The coefficient of friction started below 0.35 and decreased progressively, and stabilized around 0.25 after 600 cycles. A tribofilm consisting of copper, Cu-DLC and zinc was built up on the ball by sliding with the Cu-DLC. This tribofilm provides the good tribo-electrical characteristics.