Measurements of turbulent mixed convection flow over a two-dimensional, vertical backward-facing step are reported. Laser-Doppler velocimeter (LDV) and cold wire anemometer were used, respectively, to measure simultaneously the time-mean velocity and temperature distributions and their turbulent fluctuations. The experiment was carried out for a range of free stream air velocities 0 m/s less than or equal to u(infinity) less than or equal to 0.41 m/s for a step height of 22 mm, and a temperature difference, DeltaT, of 30 degreesC between the heated walls and the free stream air. The step geometry consists of an adiabatic backward-facing step, an upstream wall and a downstream wall. Both the upstream and downstream walls are heated to a uniform and constant temperature. The present results reveal that the introduction of a small free stream velocity causes a decrease in the turbulence intensity of both the streamwise and transverse velocity and temperature fluctuations. Also, it was found that the reattachment length increases while the heat transfer rate from the downstream heated wall decreases as the free stream velocity increases.