27Al MAS NMR has been used to study a sol?gel prepared alumina annealed at various temperatures. Two-field simulation of the sample heated to 1200 ?C confirmed the presence of corundum, as suggested by XRD, and also the presence of nanocrystalline theta-Al2O3. 27Al MAS NMR chemical shifts, quadrupolar coupling constants and asymmetry parameters are reported for the tetrahedral and octahedral aluminium sites within theta-Al2O3.