The dehydration of ethanol, 1-propanol and 1-butanol has been studied at atmospheric pressure using the novel microporous niobium silicate AM-11 (Aveiro-Manchester structure number 11) in the temperature range 150-300degrees C. The selectivity for alkenes increases with temperature for all three alcohols and reaches 100% for 100% conversion at 250-300degreesC. At lower reaction temperatures (similar to200degreesC), ethers are also formed and their selectivity decreases markedly with the alcohol size.