Experimental measurements are compared with theoretical predictions for heat and mass transfer from hot and highly humid air (130°C, 0 to 60 wt% of water vapor content) to horizontal cooling tubes (waft temperature around 40°C), which are simulating the heat-transfer tubes of a containment fan cooler in the postaccident condition of a pressurized water reactor. As the results, (1) heat and mass transfer coefficients are formulated for the present experimental conditions; (2) when the water vapor concentration in the main flow is increased from 0 to 60 wt% , the convective and condensational heat and mass transfer coefficients are approximately doubled; (3) under the condition of condensation, the absolute values of the convective/condensational heat transfer data are greater/smaller than those estimated by the equations of Rose and Fujii, respectively, though the slope of the equation agrees with that of the measuredata.