The thermal analyses of iron nitrate in stagnant and flowing air using different heating rates were conducted to establish the intermediate phases and reactions during its decomposition. In view of the thermal results, the degree of pyrolysis of the aerosol formed by atomizing ferric nitrate aqueous solution was studied. Hollow spherical particles were obtained and varied from noncrystalline to crystalline materials, depending on the pyrolysis temperature used. The decomposition efficiency of resulting particles increased with the pyrolysis temperature.