In this paper, we report a study of the effect on the powder morphology of zirconia based solid solutions of several parameters of the synthesis by gel-combustion routes, such as fuel, metal/fuel ratio, composition of the nanopowder, pH of the precursor solution, etc. We evaluated the average crystallite size. BET specific surface area and the degree of agglomeration of the final ceramic nanopowders. The intermediate stages of the synthesis were characterized by Fourier Transform Infrared Spectroscopy, Small Angle X-ray Scattering, X-ray Powder Diffraction, X-ray Absorption Spectroscopy and Infrared Thermography. We found that the precursor gel remained compositionally homogeneous up to the self-combustion step and that in order to obtain a low average crystallite size (<10 nm) and a low degree of agglomeration, the combustion temperature must be tailored to be as high as possible. Finally, a novel gel-combustion route assisted with hydrogen peroxide is reported. (C) 2011 Elsevier B.V. All rights reserved.