Effect of post-calcination thermal treatment on acid properties and pores structure of a mesoporous niobium- tungsten oxide was examined. Mesoporous Nb-W oxides treated by high temperature calcination from 673 up to 873 K exhibited a significant increase in pore size from 4.8 to 9.2 nm, a decrease in pore volume, surface area and acid amount, while the acid strength and density remained almost constant. A remarkable improvement in acid catalysis was observed for Friedel-Crafts alkylation and hydrolysis of disaccharide where the turnover frequency for both reactions increased continuously with calcination temperature. (c) 2011 Elsevier B.V. All rights reserved.