The influence of the nature of C5 hydrocarbon isomers and MOFframework structure on adsorption potential distribution, heat,and entropy of adsorption has been studied in detail. The adsorp-tion isotherms of C5 hydrocarbon isomers and their temperaturedependence enable us to differentiate between two MOF samples asadsorbents and between pentane isomers as molecular probes. Allisotherms (especially isotherms of cyclopentane) on Cu-BTC exhibitrectangular course with long vertical part; their shape is consistentwith the shape of argon isotherms. The isotherms of C5 hydrocar-bons on Fe-BTC show one saturation step which is less sharp thanin the case of Cu-BTC.Structural irregularity of the Fe-BTC in comparison with Cu-BTCframework causes the broadening of interaction energy distribu-tion profile for adsorption of both small (N2/Ar) and relatively large(isomeric pentanes) probe molecules.The isosteric adsorption heats of C5 hydrocarbon isomers cal-culated for Cu-BTC show for n-pentane and isopentane increasingtrend as a function of amount adsorbed while domination of thelateral interactions become pronounced for cyclopentane resultingin constant isosteric adsorption heat with reasonable increase incoverage. The almost constant isosteric adsorption heats for all forC5 hydrocarbon isomers on Fe-BTC suggest that the variations ofthe gas Fe-BTC interaction energy are compensated by the energyof lateral interactions.