The scope of ISO 18417:2017 covers - iodine sorbents for nuclear power plants, nuclear facilities, research and other nuclear reactors, - iodine sorbents for laboratories, including nuclear medicine, and - iodine sorbents for sampling equipment on sample lines. ISO 18417:2017 applies to iodine sorbents manufacturers and operators in order to measure the actual performance of these sorbents and their sorption capacity for radioiodine. ISO 18417:2017 applies to granulated and crushed iodine sorbents based on activated charcoal (hereinafter referred to as "sorbents") used for trapping gaseous radioiodine and its compounds. This document establishes the method and conditions for defining sorption capacity index in a laboratory.