The aim of this work is to evaluate the performance of immobilized invertase in a continuous process using a membrane bioreactor (MB) at a feeding rate of 1.6 h(-1) and at an agitation of 100 rpm. Commercial invertase (BIOINVERT (R)) was adsorbed on polystyrene beads of DOWEX (R)-anionic resin and used for sucrose hydrolysis in the MB coupled with an ultrafiltration (UF) or a microfiltration (MF) membrane. Considering the reactor in a 20 h continuous steady-state operation, the yields attained were 100% (mean activity of 0.88 mmol/h Mg-Enyme) and 99% (mean activity of 1.02 mmol/h mg(Enzyme)) when a UF and a MF-membrane were used, respectively. No leakage of enzyme from the support was detected. The inverted sugar attained was submitted to a chromatographic separation through a column packed with DOWEX-50W 8x100 resulting in a 70% high-fructose syrup (HFS). (c) 2006 Published by Elsevier Ltd.