Isomerization of n-butane over Pt ion-exchanged H-MCM-41 catalyst was studied with varying weight hour space velocities and reactant flow dilutions by using hydrogen or nitrogen as carrier gases. As a comparison, H-MCM-41 was evaluated in n-butane transformations, but it did not exhibit any activity. The main products over Pt-H-MCM-41 were methane, ethane, propane, butenes, isobutane and negligible amounts of other products, indicating that hydrogenolysis was taking place to large extent. The absence of pentanes and a low selectivity to propane as products suggests that dimerization-cracking pathway did not occur. Rather high amounts of isobutane are probably formed parallel to hydrogenolysis via a monomolecular pathway following a bifunctional mechanism. This involves butane dehydrogenation to linear butene, isomerization of linear butene to isobutene followed by hydrogenation of isobutene to isobutane.