The phase behavior of the carbon dioxide + 1-methylimidazole binary system has been investigated in a high-pressure variable-volume view cell using an analytical method. Phase equilibrium data for the system carbon dioxide + 1-methylimidazole was measured at 293.15, 309.75 and 323.15 K. The pressure under investigation was between 2.83 and 14.16 MPa. There coexisted three phases (LLV) of the binary system, which were found in a temperature range of 297.85-313.95 K. The densities of the binary mixture at phase transition points were also measured. The experimental data were correlated well by the Peng-Robinson equation of state with two binary parameters. According to the experimental results, the phase behavior of the binary system might be classified to Type-IV or Type-V according to the classification of six principal types of binary phase diagrams. (C) 2009 Elsevier B.V. All rights reserved.