Enteromorpha prolifera (EP) is a renewable energy source that was evaluated as a feedstock to produce bio-oil by thermal cracking. Harvesting EP for bio-oil production will also reduce the damage of green tide on ocean ecology. Effects of reaction temperature between 220 and 380 degrees C and reaction time between 20 and 80 min on the bio-oil yield and gas and solid thermal cracking products were investigated. Effects of solvents (i.e., ethanol and vacuum gas oil (VGO)) on the yields of bio-oil, gas and solid were also studied. EP, VGO and products from thermal cracking were analyzed by elemental analysis, gas chromatography-mass spectra and gas chromatography. Results indicate that thermal cracking of EP with VGO (EP/VGO) gave rise to the maximum bio-oil yield of 90.5% at 300 degrees C with a reaction time of 30 mm. Higher heating values and elemental analysis demonstrate that this process has the potential for industrial production of bio-oil from EP. (C) 2013 Elsevier Ltd. All rights reserved.