Heat, moisture transfers and airflow by natural convection in a rectangular cavity containing on line cylinders were studied. The work zone was arranged in such a way that 2D transfer and flow were established. At steady state, temperature, velocity and humidity fields on the symmetry plane were measured in unhumidified and humidified cavity. These results were then used to compare with CFD simulation. The thermal stratification and circular air flow in the cavity was observed. Humidification at the bottom face of cavity contributes to increase air velocity. The influence of radiation near the cold and warm walls is significant. (C) 2009 Elsevier Ltd. All rights reserved.