Lanthanum oxide is most useful as a precursor to other lanthanum compounds.  Neither the oxide nor any of the derived materials enjoys substantial commercial value, unlike some of the other lanthanides.  Many reports describe efforts toward practical applications of , as described below.
 forms glasses of high density, refractive index, and hardness. Together with oxides of tungsten, tantalum, and thorium,  improves the resistance of the glass to attack by alkali.  is an ingredient in some  piezoelectric and thermoelectric materials.
 has been examined for the oxidative coupling of methane.