Thermal reaction of zinc acetate and gallium acetylacetonate,stoichiometric ratio Zn/Ga = 0.50, in 1,4-butanediol (glycol organicmedia), 1-butanol and 2-propanol (alcohol organic media) at 300(+,ฐ)C underautogeneous pressure yielded nanocrystalline spinel zinc gallate withdiameter between 8 and 19 nm and BET surface area between 52 and 113 m2g-1. However, the reaction of them did not take place and not yielded zincgallate in toluene. As thermal reaction of zinc acetate and aluminiumisopropoxide took place in all type of organic media (1,4-butanediol,1-butanol, 2-propanol and toluene). That yielded the nanocrystalline zincaluminate with diameter between 7 and 11 nm and BET surface area between 80and 198 m2 g('-1). When the reaction of crystallite formation occursrapidly and so does the crystallization of the products then obtainas-synthesized well-crystallized spinel zinc gallate and zinc aluminatehaving high thermal stability. In this work; found that crystallite sizesof zinc gallate and zinc aluminate depend on type of the organic solvent.As for thermal stability of zinc gallate and zinc aluminate not depend ontype of organic solvent but on the crystallite size. Thermal stability ofzinc aluminate is better than zinc gallate in early calcinationtemperature. Conversely, at higher calcination temperature, zinc gallate ismore stable than zinc aluminate. And the thermal stability decreasing ofzinc aluminate is higher than zinc gallate when crystallite size isdecreased. However, the presence of the second metal in the structure couldbe increased the thermal stability of the single metal oxide.