The wettability of graphite by the silver-tin (Ag-Sn) liquid alloy was measured using the sessile drop method at a temperature interval of 1273-1473 K. The system is found poorly wetting with the contact angle at an interval of 125 ... 142 degrees. The contact angle passed through an elongated maximum as function of composition and increased with temperature. It was shown that no dissolution or chemical reaction takes place in the system up to 1473 K. The Butler equation was extended to calculate the concentration dependence of surface tension, solid/liquid interfacial energy and that of the contact angle theoretically. The theoretical results reasonably reproduce the measured values. (C) 2012 Elsevier B. V. All rights reserved.