As a part of an ongoing process, the predictive Soave-Redlich-Kwong (PSRK) group contribution equation of state was extended by the introduction of additional structural groups (F-2, Cl-2, Br-2, HCN, NO2, CF4, O-3 and ClNO) and fitting of the corresponding group interaction parameters. Interaction parameters between already existing main groups were also optimized to the growing literature data base. Overall, 75 new parameter sets are given herein, and typical results are presented for various systems. For the sake of completeness, not only the group new interaction parameters but all available PSRK/UNIFAC interaction parameter sets (more than 900) are given as supplementary material. Moreover, the required pure component properties (critical properties, acentric factors, and Mathias-Copeman constants) were revised and are also included for about 1000 components. (C) 2004 Elsevier B.V. All rights reserved.