Oil relative permeability has a significant role in thermal enhanced heavy oil recovery. The present study has investigated the effects of temperature on the heavy oil relative permeability during the tertiary gas oil gravity drainage (GOLD) mechanism. Sand-packed column models were used to examine the temperature effects on the recovery of waterflood residual oil, using the gravity-assisted gas injection process. A new, four-step experimental technique was performed, and an analytical model was used to determine the oil relative permeability from the oil production history at different temperatures. The conclusions from this work indicate that the heavy oil relative permeability is affected by temperature. Aging at the elevated temperature is determined to be the main reason behind the wettability alteration and its effect on heavy oil relative permeability.