Precursor particles for gamma-Ga2O3-Al2O3 solid solutions were prepared by spray pyrolysis of aqueous solutions of mixtures of Ga(NO3)(3), Al(NO3)(3), and HNO3, and the performance of the gamma-Ga2O3-Al2O3 solid solutions obtained by calcination thereof at 800 degrees C was investigated for the selective catalytic reduction of NO with methane as a reducing agent. The precursor prepared with a temperature gradient from 200 to 700 degrees C and with a total residence time of 23s in the ovens had a high performance. The concentration of HNO3 or of metal nitrates affected the performance. The precursor prepared from Al(NO3)(3) or Al(acac)(3) as an aluminum source exhibited high performance; however, the precursor prepared from pseudoboehmite resulted in a lower activity. (C) 2011 Elsevier B.V. All rights reserved.