Laser interferometric microscopy, applied in this work, enabled simultaneous measurements of the droplet surface tension, sigma, and the surface solvent composition. The data, obtained within the temperature interval 313.15-363.15 K and pressure range 60-135 bar, indicated a significantly lower dynamic surface tension compared to the equilibrium. The apparent mixture critical pressures (mcps), determined by zero-sigma extrapolation of the equilibrium isotherms, were in an agreement with the theoretical predictions obtained from the Peng-Robinson EOS. A quantitative description of sigma based on parachor method indicated the best fit scaling exponent ranging from 3.3 to 3.98 for different temperatures, with mean absolute deviations +/-3%. The concentration gradient of ethanol in the droplet diffusion boundary layer accounted for the variation of sigma and apparent mcp in the non-equilibrium case. (C) 2002 Elsevier Science B.V. All rights reserved.