This study investigated thermal liquefaction of cotton seed in an autoclave. The effects of solvent (ethanol/ water, water and ethanol), temperature and some additives on product distribution were investigated. The results showed that using ethanol/water as solvent could get higher total conversion. The highest liquid oil yield (38.4%) was obtained at 300 degrees C, 2 MPa and 30 min in ethanol/water with Mo/MS (medical stone). The highest hydrogen content in gas also was obtained when adding Mo/MS, and then followed by that when adding Co-Mo/MS. H-1 NMR analysis indicated that the use of additives (except MS) could increase the aliphatic content in liquid oil. H-1 NMR and C-13 NMR showed that the liquefied oil from liquefaction of cotton seed mainly obtained aliphatic compounds, and adding the additives only changed the amount of compounds and did not alter the type of compounds obtained in the oil. (C) 2015 Elsevier Ltd. All rights reserved.