La(NO 3 ) 3 .6H 2 O was used as a precursor to produce La 2 O 3 at 650 o C in an atmosphere of air. Thermal processes occurred were monitored by means of thermogravimetry, differential thermal analysis, and gas-mass spectrometry. Infrared (IR)-spectroscopy, X-ray diffractometry and scanning electron microscopy characterized the intermediates and final solid products. The results showed that, La(NO 3 ) 3 .6H 2 O decomposes through nine endothermic weight loss processes. Five dehydration steps occurred at 90, 105, 150, 175 and 215 o C, leading to the formation of crystalline nitrate monohydrate, which decomposes to La(OH)(NO 3 ) 2 at 410 o C. The latter, decomposes to La 2 O 3 at 640 o C, via two different intermediates; LaO(NO 3 ) at 440 o C, and non-stoichiometric unstable, La(O) 1 . 5 (NO 3 ) 0 . 5 at 570 o C. The gaseous decomposition products as identified by gas-mass spectroscopy were water vapor, nitric acid and nitrogen oxides (NO, NO 2 and N 2 O 5 ). The final product La 2 O 3 has a large crystalline containing pores, voids and cracks, with a surface area of 23 m 2 g - 1 . Also it possessed Lewis acidic and basic sites, as indicated by Pyridine adsorption.