A simple apparatus for determining the critical points and vapor/liquid equilibrium curves is described. The apparatus was used to investigate pure CO2, the binary system toluene-CO2, and the ternary mixture toluene-H-2-CO2. The critical points were obtained on the basis of both critical opalescence and isothermal compressibility. The critical temperature and critical pressure of CO2 determined by this method agreed well with the literature values. The critical points of the binary and ternary mixtures were determined in CO2-rich region. Peng-Robinson equation of state was used to predict critical points and the results agreed reasonably with the experimental data. (C) 2000 Elsevier Science B.V. All rights reserved.