Nanocrystalline lanthanum strontium manganite (LSM) powder has been synthesized by combustion of a transparent gel obtained by the polymerization of methylol urea and urea in a solution containing La3+, Sr2+, and Mn2+ (LSM ions). Chemistry of the transparent urea-formaldehyde (UF) polymer gel formation and structure of the gel have been proposed such that the LSM ions act in between the growing UF polymer chains by interacting through NH, OH, and CO groups by co-ordination and prevent polymer self-assembly through inter-chain hydrogen bonding as evidenced from infrared spectrum. Thermally stable structures formed by the decomposition of UF polymer below 300 degrees C undergo combustion in the presence of nitrate oxidant in a temperature range from 350 degrees-450 degrees C. A perovskite LSM phase has been formed by self-sustained combustion of the dried gel initiated with little kerosene. The powder obtained after deagglomeration and calcination at 600 degrees C for 2 h has a D-50 value of 0.19 mu m, and the particles are aggregates of crystallites 10-25 nm in size.