The molar enthalpies of solution of SrTeO3, SrTe2O5, TeO2, and SrCO3 in HCl (aq, c = 11 mol.dm(-3)) have been measured by using an isoperibol calorimeter. From these results and other auxiliary data, the standard molar enthalpies of formation Delta(f)H(m)degrees(298.15 K) of SrTeO3(cr) and SrTe2O5(cr) have been calculated to be -(1026.0 +/- 10.7) kJ.mol(-1) and -(1381.2 +/- 12.9) kJ.mol(-1), respectively. These values of enthalpies of formation are consistent with the second-law enthalpies of formation derived from their vapour pressures determined in this laboratory by a transpiration technique.