Abstract: The present invention relates to reducible porous crystalline solids, constituted of a metal-organic framework (MOF), for the separation of mixtures of molecules having different unsaturation degrees and/or a different number of unsaturations with a selectivity that can be adjusted by controlling the reduction of the MOF. The MOF solids of the present invention, after reduction, have a strong affinity for molecules containing at least one unsaturation. They can be used in various separation processes, especially those relating to hydrocarbons.