During the operation of nuclear plants, several fission products are released. Among them, radioiodine is considered one of the most important due to its tendency to form volatile species, usually combined with other hydrocarbons to yield methyl iodide (131ICH3), and its hazardous biological effect. Recent studies from our research group have shown that activated carbons are excellent materials to mitigate methyl iodide emissions. However, the adsorption mechanism is still unclear. The main goal of the present proposal is to give some light into the adsorption mechanism of methyl iodide on the surface of activated carbons, in the presence and absence of humidify, by using inelastic neutron scattering experiments at TOSCA. The evaluation of the free rotational and librational mode of methyl iodide before and after adsorption will provide crucial information about the adsorption mechanism.