In this work, ammonia and hydrogen sulfide removal from gaseous streams by zeolite materials has been examined by the use of molecular simulation techniques. In particular, grand canonical Monte Carlo and molecular dynamics simulations have been performed taking into consideration different kinds of polar and apolar zeolites. The aim of the work consisted of examining the most favorable sorption sites for the pollutant gases, simulate their sorption isotherms, and study the thermodynamic characteristics of the phenomenon. Simulation procedures have been validated against available experimental sorption data. Free ammonia and hydrogen sulfide sorption isotherms have also been compared with sorption isotherms obtained for more realistic gaseous streams (typical biogas and atmosphere, respectively) in order to evaluate competition of the molecules for sorption sites. As different sorption isotherm types have been obtained, different equations were employed for data fitting.