The well-known experimental data on turbulent heat transfer in a long cylindrical duct (more than 50 diameters long) with d between 5 and 10 mm at flow rates G from 0.1 to 15 g s(-1) and currents I from 50 to 400 A are analyzed and correlated. Data on argon dow at pressure p between 0.1 and 2 MPa are worked into equations. Generalization of this data is derived in the form of a dependence between dimensionless turbulent heat conductivity and Reynolds and Hartmann numbers in view of the effect of inertial, viscous and electromagnetic forces. The main sources of turbulent heat conductivity at the indicated conditions are analyzed. It was shown that electromagnetic forces decrease turbulent heat transfer for a fully developed flow with a wall-stabilized d.c. are. This hypothesis was made to account for the dynamics of transition from laminar to turbulent flow in the above mentioned conditions. The connection between flow regime and departure from local thermodynamic equilibrium (LTE) is established.