Coal liquefaction was usually carried out at temperature higher than 400C and at relatively high pressure. Many attempts have been made to develop methods of dissolving coal at less severe conditions in order to increase coal liquefaction efficiency and also to reduce capital and operation cost. In this investigation, three different types of pretreatments i.e. solvent swelling, in-situ solvent soaking and heating, and microwave irradiation have successfully been applied to untreated low rank Malaysian coal prior to liquefaction. The main objective of the pretreatments is to further enhance...