In the present study, instead of the burning the Elbistan lignite (L) having low calorific value and the biomasses (Balikesir Olive Bagasse "OB" and Adiyaman peat "P"), co-liquefaction process was conducted in order to produce valuable product as an oil. The effect of the biomasses ratio in the mixture on the properties of the co-liquefaction products and oil yield was also investigated in detail. The chemical characterization, composition and calorific value of the starting materials and the co-liquefaction products (char, asphaltene, preasphaltene and oil) were determined using XRD, FTIR, calorimeter, GC/ MS and elemental analysis. In addition, the morphological and thermal behavior of the starting materials was also investigated by TG/DTA and SEM. The results showed that the biomasses accelerated thermolysis of the lignite due to their amount of volatile content, cellulose, hemicelluloses and lignin in the structure causing the high total conversation ratio. The highest oil yield was obtained as 39.5% for L:P:OB (1:2:3). Calorific values of the char, asphaltene, preasphaltene and oil were determined as 1235 kcal/kg, 9080 kcal/kg, 8650 kcal/kg and 5135.19 kcal/kg, respectively. The obtained oil was identified as a paraffinic-low waxy oil whose density is 0.94 g/cm(3). (C) 2018 Elsevier Ltd. All rights reserved.