The paper presents the results of measuring the capillary constant a(2) and calculating the surface tension sigma of ethane-methane solutions. Experimental data have been obtained in the temperature range from 93.15 to 283.15 K at pressures from that of saturated vapors of pure ethane to 4 MPa. Equations that approximate the temperature, pressure and concentration dependences of a(2) and sigma are suggested. The concentration dependence of the surface tension is described in the framework of models of an ideal and a regular solution. The relative adsorption has been calculated. (C) 2013 Elsevier B.V. All rights reserved.