In this work, the vapor-liquid equilibria for the binary system carbon dioxide-1,3-butadiene was measured at three temperatures, 303, 313 and 333 K. The measurements were carried out analytically in a recirculation apparatus. The experimental data were correlated with a modified Peng-Robinson equation of state and the Predictive Soave-Redlich-Kwong model. At 311 K, a parallel was drawn with the binary systems of n-butane, isobutane, 1-butene and carbon dioxide by means of the distribution coefficients K(i). (C) 1998 Elsevier Science B.V. All rights reserved.