A perovskite-like phase of lanthanum magnesium niobate, La(Mg 2/3Nb 1/3)O 3 (LMN) has been synthesised by a mixed oxide synthetic route. Both magnesium oxide and magnesium carbonate hydroxide pentahydrate have been investigated as magnesium precursors, with the formation of the LMN phase investigated as a function of calcination temperature and dwell time by DTA and XRD. Morever, particle size distribution, morphology, phase composition and crystal structure have been determined via laser diffraction, SEM and TEM/EDX, respectively. A combination of X-ray and electron diffraction studies has demonstrated that heterogeneous powders are produced, with the presence of an MgO-rich phase and varying Mg/Nb ratios within the parent phase of LMN. Minor phases have also been identified as LaNbO 4, La 3NbO 7, MgO, Mg 4Nb 2O 9 and La 2O 3, with their concentrations decreasing with rising calcination temperature. X-ray and electron diffraction data are supportive of monoclinic symmetry in the parent LMN phase.