In this work, permeation of air through immobile surfactant monolayers has been studied by measuring the rate of shrinkage of an air bubble pressed to the horizontal air-water interface by gravity. The thin liquid film has been made of an ionic surfactant and an inorganic electrolyte. With an increase in temperature, the rate of permeation has been found to increase. A model has been developed to describe the rate of reduction in the size of the bubble with time. The model fits to the experimental data well. From the variation of the permeability constant with temperature, the validity of the energy barrier theory for gas permeation has been examined.