Sugarcane press mud was pretreated by liquid hot water (LHW) at different temperatures (140-210 degrees C) and pre-treatment times (5-20 min) in order to assess the effects on the chemical oxygen demand (COD) solubilisation, inhibitors formation and methane yield. The experimental results showed that a high degree of biomass solubilisation was possible using LHW. Higher methane yields were obtained at lower severities (log(R-0) = 2.17-2.77) with (i) mild temperatures (140-150 degrees C) and long contact times (12.5 min, 20 min) or (ii) mild temperatures (175 degrees C) with short contact time (2 min). The highest increase in methane yield (up to 63%) compared to the untreated press mud was found at 150 degrees C for 20 min. At temperatures of 200 degrees C and 210 degrees C, low methane efficiency was attributed to the possible formation of refractory compounds through the Maillard reaction. (C) 2014 Elsevier Ltd. All rights reserved.