We report on the synthesis of nanocrystalline ZnO particles by solution combustion technique using new organic fuels such as L-Glutamine, Leucine and L-Valine. The thermal decomposition and combustion of nitrate-organic fuels (precursors) were investigated through TG-DTA and XRD techniques. The results show that, the nitrate-organic fuel (precursor) gels exhibit self-propagating behavior at 400 degrees C after ignition in air. The effect of fuel and fuel to oxidizer ratio on structural properties of as-synthesized ZnO powder was investigated. It was observed that, the particle size of as-synthesized ZnO powder depends on F/O ratio, which influences the combustion process. The detailed analysis on the structure of as-synthesized ZnO powder was carried out by Rietveld refinement on XRD data and through TEM studies. Further, adiabatic temperature (T-ad) was calculated through thermodynamic theoretical calculations for different fuel to oxidizer ratios. The results were discussed on the basis of the correlations established between the T-ad, nature of the combustion and structural properties of the resulting powders. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.