In the present experiment we study turbulent moist air convection, where the turbulence is buoyancy driven and characterized by gradient Rayleigh number g(1/ρ0)(Δρ/l)d4/αν ∼ 108, in a square tube of aspect ratio 8. Hot moist air is provided at the bottom of the tube, while the top of the tube is open and is exposed to cold air reservoir. In the statistically steady state, a constant temperature gradient of -6.7 0C/m is obtained in the tube excluding some distance from the tube ends. Away from the tube ends width of the tube d is found to be relevant length scale indicating homogeneity of turbulence in the axial direction. Temperature profile is obtained from measurements. Calculations are shown that explain some features of the temperature curve. Heat fluxes are estimated. © 2015 Published by Elsevier B.V.