SiCNYO nanopowders have been elaborated by a spray pyrolysis method from an organometallic precursor which is synthesized by two different routes. Fourier-transform infrared spectroscopy and solid state nuclear magnetic resonance were used to identify the silylation and the imminolysis mechanism applied for the synthesis of each precursor. The SEM micrographs of the each "as-pyrolysed" product revealed spherical SiCNYO nanopowders with a bimodal size distribution. A drop-to-particle and a gas to particle exchanges seem to be the two mechanisms at the origin of grains size distribution. The nature and the reactivity of the carrier gas used in the aerosol indicate a significant influence on the powder morphology. It was found also that evaporation rate of the as-prepared precursor may lead to prevent the enlarging of particles. (C) 2010 Elsevier B.V. All rights reserved.