As part of a structural investigation of strontium tellurate(IV) (STO), SrTeO(3), with particular emphasis on the crystal chemistry and phase transitions, the structure of the δ-phase has been determined at 780 K using a single-crystal analysis. Both structural and non-linear optical measurements indicate that STO undergoes a γ→δ second-order ferroelectric phase transition at 633 K from the C2 (γ) to the C2/m (δ) modification. Systematic differences between the similar γ- and δ-phase structures were determined and it was found that this phase transformation can be described by a displacive mechanism.