The effects of microwave receptors to coal (receptor/coal) ratio and the period of heating by microwave energy on the solubilization of Turkish coals (Tuncbilek, Mugla-Yatagan, Beypazari lignites, and Zonguldak bituminous coal) in tetralin have been investigated. V2O5 and TiO2 were used as microwave receptors. The changes of liquid product yield indicated that it depended significantly on the type and amount of receptor and the type of coal. A significant increase in the lignite conversions to oil fractions was observed by the addition of the V2O5 receptor. The use of TiO2 receptor decreased the yield of THF soluble coal products. However, both V2O5 and TiO2 receptors decreased the yield of preasphaltene (PAS) and asphaltene (AS) due to their catalytic effect on the coal liquefaction.