Although the hydrothermal liquefaction is considered a promising technology for converting microalgae into liquid biofuels, there are still some disadvantages. This paper demonstrated that the bio-oil yield can be significantly improved by adding alcohols as co-solvents and carrying out the conversion at mild conditions (< 250 degrees C), but at the expense of a reduced bio-oil quality. By adding ethanol, the bio-oil yields obtained (up to similar to 60%) were comparable to the yield obtained at severe operating conditions using only water as solvent (54 +/- 2% on average), but the quality of the bio-oil was lower. However, the main advantages of the process here described lie in the utilisation of wet microalgae (similar to 75% moisture) and alcohol concentrations which avoid both drying the microalgae and decreasing the amount of microalgae loaded in the reactor. (C) 2016 Elsevier Ltd. All rights reserved.