A wolframite-type phase of indium niobate, InNbO4, has been synthesized by a solid-state reaction via a rapid vibro-milling technique. The formation of the InNbO4 phase in the calcined powders has been investigated as a function of calcination conditions by TG-DTA and XRD techniques. Morphology, particle size and chemical composition have been determined via a combination of SEM and EDX techniques. Single-phase InNbO4 powders have been obtained successfully for calcination condition of 900 degrees C for 4 h or 950 degrees C for 2 h with heating/cooling rates of 30 degrees C/ min. Higher temperatures and longer dwell times clearly favoured particle growth and the formation of large and hard agglomerates.