The direct measurement of caloric properties of model systems for natural gas is of great technical interest. Therefore, integral Joule-Thomson effects and isobaric enthalpy increments have been measured for two (methane + ethane + water) compositions and three (methane + water) compositions. The flow calorimeter facility used is described. The temperature range from near mixture dew point temperature to T = 600 K and pressures up to 7 MPa is covered. Expansion took place to p = 0.17 MPa. The investigated compositions of {xC(2)H(6) + yH(2)O + (1-x-y)CH4} were (x=0.07, y=0.15) and (x=0.2, y=0.2); and of {yH(2)O + (1-y)CH4} y=(0.1, 0.2, and 0.4). The measurement results have been correlated and the residual and total enthalpy functions have been derived from them.