The effect of reduction treatments in H-2 at 500 degreesC in both wet and dry atmosphere on mono and bimetallic In-zeolite supported catalysts has been studied using the perturbed angular correlation technique. The relaxation in the observed hyperfine interaction has been associated with the formation of oxygen vacancies in the indium. sesquioxide particles present on the external surface of the catalysts. The addition of Pt has consequences for the relaxation process. The effect of Pt atoms could be associated with the trapping of vacancies, thus slowing down their jump frequency. This particular and indirect In-Pt interaction does not seem to. have any effect on the enhancement of the catalytic activity observed in the bimetallic sample. A new indium species with cubic symmetry for the In site, i.e., metallic indium and/or In2O3 nanosized crystallites, was detected in reduced In/ferrierite and InPt/ferrierite samples.