Measurements of molar enthalpy increments for (0.5 H2O + 0.5 CH3OH) are reported. A counter-current water-cooled flow calorimeter was used to measure 76 enthalpy increments over the temperature range 373.2 K to 573.2 K at pressures from 0.1 MPa up to 13.0 MPa. Extrapolation of the gas phase measurements to zero pressure gave values in excellent agreement with the mean of the pure component ideal gas enthalpies calculated from spectroscopic data. Liquid phase enthalpy increments at the temperatures 423.2 K and 473.2 K and at the pressure 7.0 MPa were found to be in accordance with values calculated from the pure component enthalpy increments and excess enthalpies obtained from flow mixing calorimetry.