A refined model for tri-n-butyl phosphate (TBP), which uses a new set of partial charges generated from out ab initio density functional theory calculations, has been proposed in this study. Molecular dynamics simulations are conducted to determine the thermodynamic properties, transport properties, and the microscopic structures of liquid TBP, TBP/water Mixtures, and TBP/n-alkane mixtures. These results are compared with those obtained from four other TBP models, previously described in the literature. We conclude that our refined TB? model appears to be the only TBP model from this set that, with reasonable accuracy, can simultaneously predict the of TBP in bulk TBP, in organic diluents, and in aqueous solution. The other models only work well for two of the three systems mentioned above. This new TB? model is thus appropriate for the simulation of liquid liquid extraction systems in the nuclear extraction process, where one needs to simultaneously model TBP in both aqueous and organic phases. It is also promising for the investigation of the microscopic structure of the organic phase in these processes and for the characterization of third-phase formation; where TBP again interacts simultaneously, with both polar and nonpolar molecules. Because the proposed TBP model uses OPLS-2005 Lenhard-Jones parameters, it may be used with confidence to model mixtures of TBP with other species whose parameters are given by the OPLS-2005 force field.