Thin spent sulphite liquor (SSL) generated in pulp and paper mills is a biomass resource that is commonly concentrated and burnt. Still, the biorefinery concept may add value to the by-products contained in SSL. The goal of this work was to investigate the application of nanofiltration (NF) and reverse osmosis (RO) to the condensate of SSL (CSSL) produced by Eucalyptus globulus sulphite pulping in a Portuguese pulp mill, in order to separate acetic acid and furfural. CSSL permeation lab experiments were conducted in total recirculation, natural pH, 25 degrees C, and 26 bar, through several NF/RO membranes supplied by Alfa Laval, Microdyn-Nadir and Dow Filmtec. Alfa Laval RO99 showed a higher retention for acetic acid (89%) in comparison with DSS-HR98PP (84%) and NF97 (77%), despite its lower flux (28 kg h(-1) m(-2)). The furfural retentions were 91-93% for the three membranes highlighted. (C) 2012 Elsevier B.V. All rights reserved.