New force fields for nitrous oxide and oxygen, based on a Lennard-Jones plus point charge functional form are reported. The Lennard-Jones parameters of size and energy as well as the point charges were determined by fitting to single-component vapor-liquid equilibrium data. The new force fields accurately describe the vapor-liquid coexistance curves of nitrous oxide and oxygen. It is shown that properties not included in the parameterization process could also be reproduced. In addition to single component phase coexistance simulations, the phase equilibria of four binary mixtures (N-2-O-2, CO2-O-2, N2O-O-2, N2O-N-2) and one ternary mixture (CO2-N-2-O-2) have been simulated without further adjustment of the model parameters. Good agreement with experimental data was achieved over a wide range of conditions. (C) 2007 Elsevier B.V. All rights reserved.