The enthalpies of Li2SiO3 and Li2ZrO3 were measured between 368 and 1414 K by an isoperibol Setaram HTC 1800 drop calorimeter. The calibration procedure is described. The smoothed enthalpies between 298 and 1400 K are : H(T)degrees - H298-degrees [Li2SiO3] = -51157 + 125.860T + 0.01713T2 + 3614467T-1 J/mol H(T)degrees - H298-degrees [Li2ZrO3] = -46453 + 134.857T + 0.00740T2 + 1671251T-1 J/mol The standard deviation is almost-equal-to 3%. The heat capacities were derived by differentiation. The values extrapolated to 298 K are : C(p,298)[Li2SiO3] = (95.4 +/- 3.1)J/K mol C(p,298)[Li2ZrO3] = (120.4 +/- 3.0)J/K mol