α-TeO3 can be prepared by heating orthotelluric acid, Te(OH)6, at over 300°C . The β-TeO3 form can be prepared by heating α-TeO3 in a sealed tube with O2 and H2SO4.
α-TeO3 is unreactive to water but is a powerful oxidising agent when heated. With alkalis it forms tellurates.
α-TeO3 when heated loses oxygen to form firstly Te2O5 and then TeO2.