Aging effects of off-gas streams including dry air and humid air on reduced silver exchanged mordenite (Ag⁰Z) were studied. Aged Ag⁰Z was prepared by exposing Ag⁰Z to dry air and humid air at different aging temperatures, time, and water vapor concentrations. Iodine loading capacity on the aged Ag⁰Z was obtained through a continuous-flow adsorption system. Significant iodine loading capacity losses were observed after the Ag⁰Z was exposed to dry air and humid air. Physical and chemical analyses were conducted to observe the physical and chemical changes of Ag⁰Z after being aged. From iodine adsorption data and sample analyses, it was found that iodine loading capacity on the aged Ag⁰Z in dry air and humid air decreases with increasing aging temperatures, time and water vapor concentrations. The pseudo reaction model describes experimental data well and the oxidation of Ag⁰ is the rate determining step in the aging process.