An investigation was conducted to determine the effects of the non-condensing gas on the vapor condensation. Experiments were carried out during condensation of the mixture of the water vapor/non-condensing gas along the inner surface of a vertical tube. Air was used as non-condensing gas and the various profiles of the water vapor/non-condensing gas mixture were employed. A theoretical analysis to predict the heat and mass transfer was also presented. The amount of the condensed water obtained by the experiments was found very close to the theoretical results. The obtained heat and mass transfer results were in good agreement with earlier published results.