New data were obtained for production of H-2 and reduction of total organic carbon (TOC) by gasification of lactose in supercritical water with(out) the presence of catalysts (NaOH, KOH and Na2CO3) in a continuous Inconel 625 flow reactor. The gasification reactions were carried out at 550-700 degrees C, 22.5 MPa, lactose concentrations in the range of 0.5-2.5 wt%, feed flow rates of 5 and 7 g min(-1) and a total reaction time of 30 min. The optimum condition for the production of H-2 yielded approximately 4.5 mol H-2/mol lactose with a TOG reduction of similar to 95%. In addition, supercritical gasification of whey was carried out using the same operating conditions as the lactose system. A reduction of 92% on the TOG and 0.45 molar fraction of H-2 production was achieved, similar to the gasification of lactose at a concentration of 0.5 wt%. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.