The present work is focused on the characterization of the aeration behaviour of two different nanopowders, Al2O3 and Fe2O3, under the application of acoustic fields of different intensities (125-150 dB) and frequencies (50-300 Hz). The two nanopowders showed slightly different behaviours: in particular, Fe2O3 is generally characterized by a better fluidization quality. These differences have been explained by referring to nanoparticles aggregates properties. In particular, aggregates size and density and fractal dimension have been numerically evaluated. The fluidization of binary mixtures of the two powders has also been investigated under the application of different acoustic fields (130-135 dB, 120 Hz) and varying the amount of the two powders from 7%wt to 90%wt of Fe2O3. The addition of Fe2O3 generally has a beneficial effect on the fluidization quality of the binary mixtures, in terms of pressure drop and bed expansion ratio, becoming relevant from an amount of Fe2O3 of 33%wt. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.