Cost-effective conversion of cellulosic biomass to value-added lactic acid with heterogeneous catalysts has attracted much attention recent years. While both solid Lewis acids and bases have been extensively studied, the role of redox catalysts for the production of lactic acid is barely understood. Herein, the LaCoO3 perovskite metal oxides with strong redox properties and a good stability in hydrothermal media were used as the catalysts for the conversion of a variety of cellulosic biomass to lactic acid. The effects of reaction conditions such as reaction temperature, catalyst loading, and gas atmosphere were investigated. At the optimum conditions, the yields of approximately 40%, 38%, and 24% lactic acid were obtained from glucose, xylose and cellulose, respectively. The key intermediates such as pyruvic acid were used as the probe reactants to explore the reaction mechanism. Unlike Lewis acid or base catalysed sugar conversion reactions, the redox pathway might start from the oxidative decarboxylation of aldose sugars and the lattice oxygen atoms in the LaCoO3 perovskite structure participate the redox cycles in the conversion of sugars to lactic acid. Lastly, the stability of the LaCoO3 catalyst in hydrothermal reaction media was discussed. (C) 2016 Elsevier B.V. All rights reserved.