Experimental assays were performed to evaluate the cellulose enzymatic hydrolysis of liquid hot water-pretreated switchgrass at high solid content. Liquid hot water pretreatment (200 degrees C, 5 min), followed by washing of pretreated solids, proved to be a suitable alternative for a biorefinery approach. It was found that the washing of solids and initial pH had a significant effect on hydrolysis efficiency. The effect of solid content, enzyme dosage, and partial cellulase substitution by xylanase were studied experimentally using a response surface methodology with a Box-Behnken experimental design. Glucose concentration and hydrolysis efficiency were significantly affected by solid content and enzyme dosage. Very high glucose concentrations (189 g/L) were achieved. High hydrolysis efficiencies were found even for high solid content (>90% for 25% solid content) but only at high enzyme dosage (40-70 Mg-protein/g(glucan)). Empirical correlations representing hydrolysis efficiency and glucose concentration as a function of solid content and enzyme dosage were obtained.