Hydrogen production with light as an additional energy source in a microbial electrolysis cell (MEC) is described A ruthenium-dye (N719) sensitized solar cell with an open circuit potential (V(oc)) of 602 mV was connected to the MEC Hydrogen production was carried out by irradiating the DSSC connected across the MEC with a light intensity of 40 mW/cm(2) and also with natural sunlight The DSSC was stable during various batch experiments The acetate conversion efficiency and the coulombic efficiency based on the average of first two batches were 30 5 +/- 2 5% and 40 +/- 2% respectively The cathodic recovery efficiency ranged from 72% to 86% during repeated batch experiments with an average of 78 2 5% (C) 2009 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved.