Measurements of the excess molar enthalpy H-m(E) of {xH(2)O + (1 - x)CO2} in the supercritical region carried out at temperatures from 649.4 K to 698.2 K, at pressures in the range 20 MPa to 25.5 MPa, and at x = 0.5 are reported. These measurements, together with those reported previously, are well fitted using a two-reference fluid corresponding states model.