Abstract: The silver nitrate impregnated mordenite is prepared, the adsorption characteristics of this inorganic adsorbent for airborne radioiodine is examined. The effects of various operating conditions on decontamination factors (DF) of radioiodine are investigated. Results show that this adsorbent has good adsorption properties for both elemental iodine and methyl iodine, the adsorption capacity is up to 196.6mg(Ⅰ)/g(AgX), the effects of water content and NOx in feed gases on DF are very small. The adsorbent can be used to remove radioiodine from nuclear fuel reprocessing off-gases and from air cleaning systems of nuclear reactors.