The oxidative dehydrogenation of lactic acid to pyruvic acid was studied over nickel-niobium mixed oxide catalysts with different Ni/Nb ratios. Furthermore the catalysts were characterized by XRD, ICP, TPR and nitrogen adsorption. Thus, it was found that the reducibility and the surface productivity were directly correlated to the Ni/Nb ratio, whereby increased Nb amount was found favourable for the catalytic performance. Furthermore, the formation of by-products was studied showing that acetaldehyde was formed by thermal decarboxylation of lactic acid and acetic acid yielded from the catalytic oxidation of the as-formed acetaldehyde. (c) 2013 Elsevier B.V. All rights reserved.