This study examines the effects of various process parameters regarding separately and co-liquefaction in a nitrogen gas medium under catalytic and non-catalytic conditions of Elbistan lignite and various biomass samples, the direct use of which is inconvenient both economically and ecologically. According to the obtained results, the optimum process parameters are as follows: The particle size is 1.5 mm, liquid/solid ratio is 3/1, reaction time is 90 min, and reaction temperature is 400 degrees C. Fe2O3 has been selected as the most suitable catalyst type and waste paper as the most suitable biomass type. At 3/1 liquid/solid ratio, as a result of the liquefaction studies, which are made through using fresh and recycled solvent, the obtained total conversions are 90.2 and 88.4%, oil + gas conversions are 59.3 and 57.6%. Elemental analyses have been made in order to gain information on the structure of the preasphaltene and chars, which are obtained as a result of the liquefaction of Elbistan lignite separately and together with paper under catalytic conditions. According to the results of the elemental analysis, chars and preasphaltenes may not be used as fuel. However, as preasphaltenes have high content of both carbon and hydrogen, their re-liquefaction under catalytic and non-catalytic conditions separately or together with the biomass, and the co-liquefaction of the char with the biomass or burning it in a fluidized bed may be recommended. According to the results of gas chromatography/mass spectrometry analyses of the oils obtained as a result of liquefaction, the oils basically consist of various components, such as naphthalene and its derivatives, tetraline and derivatives, indene, butylated-hydroxytoluen, binaphtalene, and indole.