The single-gas adsorption properties of various species (H-2, CH4, CO2 CO, H2O) involved in quite important industrial processes, such as methane steam reforming and water gas shift reaction, are evaluated for Faujasite NaX and NaY zeolites. To carry out such an investigation, a multivariate regression analysis (using Levenberg-Marquardt algorithm) is adopted, fitting experimental adsorption isotherms from the literature with the Langmuir and Sips models. A number of experimental isotherms is used to enlarge as much as possible the Validity range in terms of temperature and pressure. The evaluated parameters are compared with those available in the open literature, in order to provide a further confirmation of the results of the present work. Such a comparison is required to extend the literature information and, where necessary, to cover the current lack of adsorption data for the considered zeolite. The chosen functionality of the adsorption parameters with temperature and pressure should be useful in a wide range of applications.