Flow calorimetric measurements of the excess molar enthalpy H-m(E) for {xCO(2) + (1 - x) C2H4} are described. The measurements cover the range T = 260.95 K to T = 315.75 K at pressures from 3.5 MPa to 12.6 MPa. Liquid phase measurements were made at the pressure 11.0 MPa over the range T = 260.95 to T = 300.45 K, and at pressures slightly greater than the saturation pressure of ethene or the critical pressure locus for the mixture. At x = 0.5 and at the four temperatures (285.85, 300.45, 306.25, and 315.75) K, excess enthalpy measurements were made over a range of pressures from 3.0 MPa to 12.6 MPa. The measurements at (285.85 and 300.45) K traverse the critical locus for the mixture, and those at (306.25 and 315.75) K are in the supercritical region. The measurements are compared with curves generated from the Patel-Teja equation of state, which does not quite fit the measurements but reproduces the main features of the observed behaviour.