Viscosities of ternary systems consist of polycarbonate (PC)/brominated polystyrene (PBrS) in chloroform and their correspondingbinary systems weremeasured at different temperatures (20, 25, and 30◦C).All themeasurements were carried out at the concentrationranges of 0.1–0.6 g·dL−1. The mass ratio of PC to PBrS was selected as 75:25, 50:50, and 25:75 in the ternary solutions. Two empiricalexpressions of Huggins and Kraemer equations with three-parameters were used for reproducing of the experimental viscosity data.The fitting parameters were obtained for the corresponding temperatures. The miscibility criteria on the basis of the sign of [η]mbased on the difference between experimental and ideal values of [η]m, was calculated by applying the Garcia et al., theoreticalequation. The effect of temperature on the viscosity data was also studied. The results from this method were correlated with themiscibility data obtained for the same system by differential scanning calorimeter (DSC) findings.