An intensified reaction technology was investigated to achieve high concentrations of levulinic acid (LA) from eucalyptus wood. In the new process, the woody biomass was first pretreated in mild conditions to hydrolyze hemicellulose and recover xylose. The pretreated wood with a high content of cellulose was further treated under relatively severe conditions to produce LA and formic acid. The reaction solution was reused in treatment of new batches of biomass, resulting in high concentrations of LA (105 g/L) and formic acid (39 g/L), respectively. The lignin and humins were recovered as solid byproducts, which had an estimated high heating value of 25-27 MJ/kg in comparison with 18 MJ/kg of original wood. In the sequential repeated batch reactions, however, the LA yield deteriorated batch by batch. It was found out that the old LA in the reaction solution inhibited formation of new LA from glucose. In addition, some LA at high concentrations was lost due to its interactions with other intermediates and byproducts. (C) 2016 Elsevier Ltd. All rights reserved.