A study was carried out to assess the chemical composition of pre-hydrolysate liquor (PHL) produced in a dissolving pulp production facility in Eastern Canada. The true PHL contains high amount of both mono- and oligo-sugars (1.50-1.65%). Xylose/xylan was the predominate sugar in the PHL. Glucose, galactose, and mannose were also found in the PHL. Furfural, which was generated from further degradation of five carbon sugars, was also found in the PHL. Acetic acid released during pre-hydrolysis from the labile acetyl groups present in the hemicelluloses was about 25% of the total solids in the PHL. The sum of sugars, acetic acid, lignin and ash contents account for 91.4-95.6% of the total solid content of the PHL. The presence of sugars in the neutralized PHL was negligible while a large amount of furfural was found. (C) 2010 Elsevier Ltd. All rights reserved.