In this study, the effect of various parameters such as operating temperature, crude oil viscosity, injection flow rate, and operating pressure on heavy oil/water relative permeability were investigated followed by proposing new correlations for calculating heavy oil/water relative permeability. The experimental results obtained in this study showed that both water and oil relative permeabilities are significantly temperature dependent and they increase when temperature increases. It was also found that relative permeability to oil and water increase with decrease in oil viscosity. Additionally, tests results indicated that increase in injection flow rate results in higher oil relative permeability and lower water relative permeability. Unsteady state core flooding experiments carried out at various operating pressures showed that the relative permeability to oil in heavy oil/water system is independent of operating pressure. The heavy oil/water relative permeability data obtained in this study was used to develop new heavy oil/water relative permeability correlations by modifying the original Corey's correlations. The comparative evaluation of the new correlations with the original Corey's correlations indicated significant improvement in both heavy oil and water relative permeability estimation. Statistical analysis of the results showed that the new correlations facilitate reliable calculation of heavy oil/water relative permeability values by decreasing the root mean square magnitude from 0.167 and 0.178 to 0.004 and 0.061 for water and oil relative permeability, respectively. In addition, the accuracy of newly developed correlations was tested against five sets of experimental data obtained from literature. Results of this comparison also showed that heavy oil/water relative permeability predicted by new correlations is in better agreement with experimental data compared to those predicted by Corey's model. (C) 2015 Elsevier Ltd. All rights reserved.