In 2004, we started to develop a group contribution method aimed at estimating the temperature-dependent binary interaction parameters (k(ij)(T)) for the widely used Peng-Robinson equation of state (EOS). This model was called PPR78 (predictive 1978, Peng Robinson EOS), because it relies on the Peng-Robinson EOS as published by Peng and Robinson in 1978 and because the addition of a group contribution method to estimate the kij value makes it predictive. In our previous papers, 12 groups were defined: CH3, CH2, CH, C, CH4 (methane), C2H6 (ethane), CHaro C-aro, C-fused aromatic rings, CH2,cyclic ,CHcyclic =C-cyclic and CO2. Thus, it was possible to estimate the kij value for any mixture that contains alkanes, aromatics, naphthenes, and CO2, regardless of the temperature. In this study, the PPR78 model is extended to systems that contain nitrogen. To do so, the group N-2 was added.