Spinelic structures of AB2O4 type are widely used in the field of lithium ion batteries [1], magnetic catalysis [2], sensors and actuators [3], hyperthermia treatment [4], antitumor applications [5] for CoFe2O4 and of vacuum flat cathode-ray tube used in field emission displays [6] for ZnGa2O4. This study presents the synthesis and physical-chemical characterization of CoFe2O4 and ZnGa2O4 spinelic nanoparticles, obtained by hydrothermal method. The precursors used in order to obtain CoFe2O4 were cobalt nitrate and iron nitrate, and for ZnGa2O4 the precursors were zinc nitrate and gallium oxide. The resulting suspension was transferred into a Teflon-lined stainless steel autoclave and then was introduced in an oven at 2100C for 4 h. in alkaline media (pH=12). The crystal structure and morphology were investigated by means of X-ray diffraction, scanning electron microscopy and atomic force microscopy. Thermal stability of nanomaterials was studied using high temperature chamber for X-ray diffraction with platinum heating strip, up to a temperature of 5000C. All the specimens showed the (311) peak with highest intensity in the XRD patterns, proving from spinelic structure. The diffraction peaks in the patterns for both nanomaterials were indexed to spinelic phases (space group Fd3m). The average crystallite size determined from XRD line broadening is in the range 50-60 nm. The morphological aspect of the resulting powders was examined by SEM. The micrographs reveal the formation of soft agglomerates, presenting a spherical shape for CoFe2O4 and and ZnGa2O4 form of crystallization is cubic.