In this study we examine the prediction of critical points in fluid mixtures from the Stryjek-Vera version of the Peng-Robinson equation of state (PRSV EOS) combined with the COSMO-SAC liquid activity coefficient model (LM) through the modified first order Huron-Vidal (MHV1) mixing rule. This approach requires input of only pure component properties, such as the critical properties and acentric factor. No binary interaction parameter or experimental data on vapor-liquid or liquid-liquid equilibrium is needed. Six different types of binary mixtures are studied, including alkane/alkane, ketone/alkane, alkanol/alkane, alkanol/aromatic, alkanol/alkanol, and water/alkane mixtures. In general, the predicted critical loci are in semi-quantitative to quantitative agreement with experiments. The mean absolute relative errors are found to be 2.99% for critical temperature and 11.22% for critical pressure. Therefore, this approach (PRSV + MHV1 + COSMOSAC) could provide reasonable a priori predictions of critical loci without the use of any experimental data of the mixture. (C) 2011 Elsevier B.V. All rights reserved.