AbstractWe present empirical models for calculating the viscosity of hydrocarbons and their mixtures, including with carbon dioxide, over a wide range of temperatures and pressures. The procedure is simple, will always yield a reasonable answer, and is surprisingly accurate for the fluids and conditions we have examined. Indeed, our model is more accurate than other models currently in use, including the much more complicated corresponding states methods. Further, in many cases, the model is completely predictive, requiring only the normal boiling point as input data. The predictive ability of the model is also tested with several petroleum mixtures.