Samples of zeolite Y in which part of the Na+ ions were exchanged by metal ions such as Ni2+, Cu2+, or others were reduced by H2 to 550 Deg. The resulting samples were investigated by magnetic and ESR methods. The results indicate that the metal atoms produced by the redn. diffuse out of the pores and form relatively large sized crystals at the outer surface of the zeolite particles. If, previous to the redn., 2 types of metal ions are present, for instance Ni2+ and Cu2+, redn. may, under favorable circumstances, lead to the formation of crystals of alloys. Alloy formation had a profound influence on the type of conversion of hexane. Ni-on-zeolite catalysts show a hydrogenolytic reaction producing CH4 and straight chain paraffins of lower mol. wt. Ni-Cu zeolite catalysts are less active, but show considerable isomerization to singly branched isoparaffins. Small amts. of 2,2-dimethylbutane were also found in the products. The pattern of the reaction thus becomes more similar to that demonstrated by Pt-on-zeolite catalysts. A similar influence on the reaction pattern was demonstrated by the admixt. of Ag although to a lesser degree.