Yttrium iron garnet (YIG) precursor particles were obtained by homogeneous precipitation in a nitrate salt solution by a reaction involving the thermal decem position of urea. Chemical analysis indicated that solid phases were initially precipitated with sequential iron ion content. The precipitate formed was an amorphous mixed iron oxide phase. The complex composition and the thermal decomposition of the precipitate were studied by thermogravimetry-differential thermal analysis, differential scanning calorimetry, X-ray diffraction, and Fourier transform - infrared spectroscopy. Precipitate morphology was observed by SEM and TEM. Fine-grained single-phase yttrium iron garnet (YIG:Y3Fe5O12) powders were obtained by calcination of the precipitate at 1200 degrees C. YFeO3 intermediate compound was formed at 600 degrees C prior to the final crystallization of YIG.