Magnesium niobate (Mg4Nb2O9) powders have been prepared and characterized by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) techniques. The effect of calcination temperature, dwell time and heating/cooling rates on phase formation, morphology and chemical composition of the powders are examined. The calcination temperature and dwell time have been found to have a pronounced effect on the phase formation and morphology of the calcined magnesium niobate powders. It has been found that the minor phases of nano-sized MgO inclusion and the columbite-type MgNb2O6 phase tend to form together with the corundum-type Mg4Nb2O9 phase, depending on calcination conditions. It is seen that optimisation of calcination conditions can lead to a single-phase Mg4Nb2O9 in a hexagonal phase. © 2004 Elsevier B.V. All rights reserved.