Layered double hydroxides with the hydrotalcite-type structure containing Mg2+ and V3+ in the brucite-like layers, possessing different V contents, have been prepared and characterised by elemental. chemical analysis, powder X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy and specific surface area and porosity assessment by nitrogen adsorption; thermal decomposition was studied by Differential Thermal Analysis and Thermogravimetric Analysis. The solids obtained after calcination at 800 degreesC were tested as catalysts for oxidative dehydrogenation of propane and n-butane. Results indicate that the relative amounts Of Mg3(VO4) and MgO, depending on the V content in the starting hydrotalcite, determines the performance of the catalysts in oxidative dehydrogenation of propane and n-butane. (C) 2003 Elsevier Ltd. All rights reserved.