A generalized viscosity correlation has been used to predict the viscosity-temperature relationship of bitumen mixed with various proportions of diluents such as GCOS synthetic crude, mobil solvent and naphtha. The results showed that the correlation can accurately predict the viscosities of bitumen-diluent mixtures based on a single viscosity measurement at 30°C and one atmosphere. For 300 experimental points, the correlation yielded an overall average absolute deviation between predicted and experimental values of 8.7%. It is found that the correlation gave high percent errors for mixtures with high disparity in viscosity between bitumen and diluent.