The surface tension of lanthanum, praseodymium, samarium and erbium trichloride melts, above the melting point (1160-1260, 1059-1179, 955-1135 and 1049-1230K respectively) was predicted by a theoretical model. The equation requires enthalpies of sublimation and densities of salts, with the data available in the literature. The results are validated by comparison with some of the reported values, and they agree well with the existing experimental data. (C) 2015 Elsevier B.V. All rights reserved.