The surface tension of molten Sn-Bi (mole fraction X-Bi = 0.455) alloy has been determined by the sessile drop method at oxygen partial pressure (P-O2) of 1.0 X 10(-6) MPa and different temperatures. The experimental results have been analyzed and discussed, and the positive temperature coefficient Of surface tension of molten Sn-Bi alloy has been elucidated. The surface tension of this molten alloy has also been obtained by calculation Using STCBE based on Butler's equation and thermodynamic data. The experimental results agree well with the calculation values. (c) 2005 Elsevier Inc. All rights reserved.