Different steam explosion conditions were applied to Salix chips and the effect of this pretreatment was evaluated by running both enzymatic hydrolysis and biogas tests. Total enzymatic release of glucose and xylose increased with pretreatment harshness, with maximum values being obtained after pretreatment for 10 min at 210 degrees C. Harsher pretreatment conditions did not increase glucose release, led to degradation of xylose and to formation of furfurals. Samples pretreated at 220 and 230 degrees C initially showed low production of biogas, probably because of inhibitors produced during the pretreatment, but the microbial community was able to adapt and showed high final biogas production. Interestingly, final biogas yields correlated well with sugar yields after enzymatic hydrolysis, suggesting that at least in some cases a 24 h enzymatic assay may be developed as a quick method to predict the effects of pretreatment of lignocellulosic biomass on biogas yields. (C) 2011 Elsevier Ltd. All rights reserved.