Within the scope of this work the hydrogenation of butadiene, the isomerization and the hydrogenation respectively of the consecutive products of n-butylenes at a Pd/Al2O3-supported catalyst were investigated.The hydrogenation of butadiene shows at low partial pressures of butadiene instabilities of the reaction. These instabilities can be traced back to the complex interaction of reaction, adsorption and transport of mass within the pore-structure of the supported catalyst. On raising the partial pressure of butadiene the instabilities vanish, since the layer of adsorbates becomes thicker and more uniform. The hydrogenation of butadiene is accompanied by the formation of n-butylenes whereas their ratio is constant: 60% 1-butylene, 40% 2-butylene as long as the total catalytically active length of the pore is covered by butadiene. The consecutive reactions of the n-butylenes (hydrogenation and isomerization) are completely suppressed. If the partial pressure of butadien subside within the length of the pore against 0, due to transport of mass within the pore, then, on the one hand the isomerisation of the n-butylene to the thermodynamically more stable 2-butylene and on the other hand the formation of butane initiates. The aim of the investigations of hydro-isomerisation of butylenes was to establish reaction conditions that suppress the hydrogenation towards butane to the greatest possible extend. The isomerisation increases significantly at low partial pressures of hydrogen and reaches a constant value with a further gain in partial pressure of hydrogen. In contrast to that the hydrogenation is subjected to a linear dependence. Reducing the partial pressure of hydrogen or the addition of CO results in a diminution of the hydrogen-surface-coverage on the catalyst. In accordance to the different dependencies of both competing reactions on the partial pressure of hydrogen, hydrogen-surface-coverage, respectively - a pronounced rise in selectivity concerning the isomerisation-reaction can be observed.