Abstract: The average crystallite size (LC) is an important property of carbon materials for aluminum electrolysis. LC is a useful factor to characterize the petroleum coke (PC) calcination level and in some cases to estimate the baking level of anodes. CO2 reactivity of coke and specific electrical resistance (SER) are two important parameters in manufacturing of anode in aluminum industries. In addition the amount of sulfur and calcination temperature of coke is very effective. We demonstrate the effect of coke calcination with different sulfur level on CO2 reactivity and specific electrical resistance. Many types of coke samples which were calcinated in different temperatures have been examined in this study. The LC of coke samples has been estimated by the XRD then CO2 reactivity and specific electrical resistance of coke were determined. Our data shows that when calcination of coke increases, CO2 reactivity and specific electrical resistance of coke will decrease.