Vanadium-exchanged Ti, Zr, and Sn-pyrophosphates have been prepared as cubic phase and tested for the oxidative dehydrogenation of ethane in the temperature range 550-700 degrees C in a fixed bed reactor. The catalysts have been characterised by XRD, XPS, BET surface area and TPR experiments. Vanadium exchange does not modify the cubic structure of the materials but thermal treatment under reducing or reaction conditions results in a significant loss of Sn-pyrophosphate structure, whereas Ti and Zr-pyrophosphates remain stable. All samples are active for the reaction and vanadium-Ti-pyrophosphate provides the best catalytic performances. The exchanged catalysts show a very good selectivity to ethylene, even at quite high ethane conversion, which has been attributed to the great vanadium site isolation. (c) 2005 Elsevier B.V. All rights reserved.