Kinetics and reaction mechanism of catalytic hydrogenation and oxidation Of D-lactose were studied in three-phase laboratory reactors. Catalyst screening results and influence of temperature, pressure, catalyst loading and pH are reported as D-lactose was either catalytically hydrogenated to lactitol or oxidized to lactobionic acid. The product yield was significantly influenced by reaction conditions and catalyst choice. Additionally, during oxidation and hydrogenation processes, catalyst deactivation was severe under non-optimized conditions. Temperature dependency of lactose mutarotation was determined by NMR analysis. (c) 2006 Elsevier B.V. All rights reserved.