While the formation of water-in-crude oil (W/O) emulsion is identified to cause serious problems in petroleum industry such as decrease in the efficiency of oil recovery, increase in pumping cost, and pipeline corrosion its treatment has been based mostly on gravity separation by mechanical/chemical technology. As an integral part in the process of oil production and transportation, crude oil demulsification has received attention. In this work, microwave demulsification and the influence of a variety of inorganic salts to the microwave process has been studied. A comparative study on microwave demulsification of heavy oil and light oil has also been conducted. The obtained results showed water separation of 47 % between irradiated and non-irradiated emulsion for heavy crude oil compared to 13 % for light crude oil. The effect of different inorganic salts and the optimum amount of the electrolyte to promote demulsification were also determined.