The oscillatory behavior during CO oxidation over Pd supported on glass fibers was studied in a recycle reactor. The properties of oscillations as a function of temperature and inlet CO concentration were investigated in detail. The peculiarity of the observed oscillations is their long period up to 6 h. Mathematical model considering oxidation-reduction processes of the Pd has been developed to describe the experimental results. The model accounts for the observed reaction rate dependence on the CO inlet concentration, the region of oscillations and the dependence of the oscillatory behavior upon temperature and CO inlet concentration.