​Separation of propylene/propane is one of the most challenging and energy consuming processes in chemical industry. Propylene demand is increasing and a 99.5 % purity is required for industrial pur-poses. Adsorption based solutions are the most promising alternative to improve the economi-cal/energetic efficiency of the process. ZIFs combine the desired characteristics from both MOFs and zeolites: tunability and flexibility from the metal organic frameworks, and exceptional thermal and chemical stability from zeolites. In order to enlighten the role of the cation in the sodalite ZIF-8 framework for propane/propylene separation, dynamic breakthrough measurements have been per-formed over ZIF-8(Zn), ZIF-67(ZIF-8(Co)) and MUV-3 (ZIF-8(Fe)), all materials based on the same linker methylimidazole. Cation substitution has a remarkable influence in the framework flexibility, and, consequently, in SOD-ZIF selectivity for light hydrocarbons. The differences between the crys-tallographic pore sizes of the material and the molecular dimensions of propane and propylene are so small, that the slightest change in the framework will cause notable advantages/disadvantages in the final application. While cobalt is known to promote a more rigid framework resulting in an adsorption selectivity towards propane, iron presents the inverse effect yielding selectivity to propylene. Zinc has an intermediate effect. A threshold pressure in the isotherm is observed for propylene uptake by ZIF-67 at 273 and 298 K, and only at the lower temperature for ZIF-8. Inlet mixture composition does not highly influence the adsorptive selectivity, although it clearly affects the pure hydrocarbon recovery. Over ZIF-67 breakthrough experiments at 298 K yield a temporary pure propylene flow representing 10-15% of the amount fed. Based on the adsorption selectivity for propane, ZIF-67 is a promising candidate for propylene/propane adsorptive separation.​