This work features the experimental determination of overall heat transfer coefficients and heat transfer coefficients from the surface of a heat transferring sieve tray to the turbulent froth on the tray. The present investigation is part of a long-term project on heat integrated distillation columns (HIDiC), focusing on the impact of on-tray heat transfer on Murphree tray efficiency. A 150 mm diameter distillation column with a diabatic section has been used in experiments to determine heat transfer coefficients for pure water and methanol/water systems. The tray was operated in both heating and cooling modes, in which heat fluxes up to 50 kW m(-2) and 110 kW m(-2), respectively were transferred. The experimental heat transfer coefficients were correlated with the plate-to-froth temperature difference in the heating mode, in which nucleate boiling is promoted; and with the vapour velocity in the cooling mode, where convective cooling and condensation takes place along the vapour path.