Ruthenium nanoparticles included in alumina membranes have been prepd. either by dihydrogen decompn. of the complex Ru(COD)(COT) (COD = 1,5-cyclooctadiene; COT = 1,3,5-cyclooctatriene) to give pre-prepd. colloidal solns. which were further used to fill the pores of nanoporous alumina membranes by vacuum induction, or by in situ decompn. These hybrid systems were tested in the hydrogenation of 1,3-butadiene in the gas phase. The use of Ruthenium loaded membranes resulted in considerably increased activities compared with grinded samples.