γ-FeMnO3 samples with and without Pd metal impregnation have been prepared by co-precipitation method and investigated by powder X-ray diffraction and 57Fe Mossbauer spectroscopy techniques, for its bulk characteristics. Catalytic activity of these samples has been studied for CO oxidation reaction by injecting CO or (CO+O2) pulses over their surface, with a view to delineate the role of Pd metal and reducible cations during this reaction. Pd metal impregnation over the surface of γ-FeMnO3, leads to significant improvement in its catalytic activity, particularly at lower temperatures. Based on these experiments, clear evidence for the low temperature (T~350 K) disproportionation of CO over the surface of Pd metal particles and lattice oxygen incorporation during CO oxidation reaction, have been presented. From the comparative study of Fe2O3, Mn2O3 and FeMnO3, the existence of any synergistic effects between Fe3+ and Mn3+ cations, is ruled out for FeMnO3, mixed oxide system.