This study concerns tire measurement of the velocity and temperature fields in a laminar flow within a vertical channel of rectangular cross section. The fluid is heated in volume by direct electric conduction induced by an alternating electric field. Particular attention is paid to tire procedure for temperature measurement under an electric field. The feasibility of such a measurement technique is shown, and specific aspects of the mixed convection regime are analyzed. Flow and temperature fields are also calculated by solving numerically tire complete Navier-Stokes and energy equations for comparison with tire experimental results. Differences between the experimental and numerical results are discussed, and the underlying physical mechanisms are analyzed.