X-ray photoelectron spectroscopy (XPS) has been used to probe surface cations of A-type molecular sieves. Surface compositional data and binding energies of external framework atoms helped in identifying location of cations (site II) responsible for adsorption behavior of molecular sieves. A correlation of carbon dioxide and water adsorption behavior with concentration of probed cations has been made for Na-A and cesium-exchanged A-type molecular sieves.