In this study, the effects of temperature on the efficiency of capillary imbibition mechanism were investigated. For this purpose. 3-D capillary imbibition tests under static conditions and at different temperatures (between 20 degrees and 90 degrees C) were conducted using Berea Sandstone samples taken from the same block. In each set of experiments, different types of fluid pairs representing a wide range of oil/water viscosity ratios and interfacial tensions (IFT) were used. Reduction in viscosity and IFT due to temperature increase remarkably altered the capillary imbibition rate. Residual oil saturation was more significantly influenced by the IFT reduction than thermal expansion effect. Also, a study was conducted to investigate the validity of the scaling law when the temperature effect is involved.