We present sonochemical synthesis of YFeO3 and Y3Fe5O12 by employing the corresponding mixtures of M(acac)3 precursors. Resulting phase composition of the product can be controlled by the starting stoichiometry of the precursor complexes. Reactions carried out with a 1:1 molar ratio led to amorphous materials that crystallized to perovskite YFeO3 upon calcination. The Y3Fe5O12 garnet phase was produced when a 3:5 molar ratio was employed. SEM was used to examine particle shape, size, and size distribution. The oxide products featured nanoscopic composite particles of a uniform size distribution and nearly spherical shapes with an estimated diameter of 20 nm. TEM study revealed the amorphous structure of the oxide products and the crystalline nature of the calcined phases. HT XRD revealed crystallization of YFeO3 or Y3Fe5O12 on heating and the increase in particle diameter.