The Peng-Robinson equation of state (PR EOS) is widely used for modeling phase behavior of hydrocarbon mixtures. When applied to heavy hydrocarbons and their mixtures, however, the PR EOS can exhibit erroneous phase behavior predictions. In this research, we develop new correlations for critical temperatures (T-C), critical pressures (P-C), and acentric factors (omega) that enable the PR EOS to accurately predict phase behavior of n-alkanes up to C-100. Predictions using the PR EOS with the new correlations give 3.0% average absolute deviation (AAD) for 3583 density data, and 3.4% MD for 1525 vapor pressure data for n-alkanes from C-7 to C-100. Significant improvement is also observed for bubble point pressure and density predictions for n-alkane mixtures. The new correlations developed for T-C, P-C, and omega are then applied for characterizing 25 different reservoir oils. Results show that, compared to the conventional critical parameter correlations in the literature, our correlations give more accurate phase behavior predictions while requiring less adjustment of the parameters. The optimum T-C and Pc developed for n-alkanes can serve as useful lower limits for T-C and P-C of pseudo components of reservoir oils that are characterized using the PR EOS. (C) 2012 Elsevier B.V. All rights reserved.