Process for producing alkene(s) from an oxygenate feedstock in a reactor by dehydration in the presence of a supported heteropolyacid catalyst. The pore volume of the supported heteropolyacid catalyst satisfies the following formula: PV>0.6−0.3[HPAloading/Surface Area of Dried Catalyst]where; PV is the Pore Volume of the dried supported heteropolyacid catalyst (measured in ml/g catalyst); HPA loading is the amount of heteropolyacid present in the dried supported heteropolyacid catalyst (measure in micro moles/g); and Surface Area of Dried Catalyst is the surface area of the dried supported heteropolyacid catalyst (measured in m2/g).