Oscillatory behavior during ethylene oxidation over a Ni foil has been discovered in the temperature range of 600-800 degrees C. The oscillatory behavior occurred in C2H4 excess in contrast to the well-known oscillations during C2H4 oxidation over Pt and Rh. The periodic variation in oxygen imbalance together with in situ TGA measurements and the variation in color during the oscillations indicate that the oscillations are closely connected with reversible oxidation of Ni to NiO. The observation of oscillations in pulse supply mode prove also important role of periodic carbon deposition/removal. A characteristic feature of the oscillations during ethylene oxidation is high sensitivity of the oscillation waveform to the catalyst temperature. The oscillations were accompanied by propagation of the oxidation and reduction fronts which could be observed with the naked eye. [GRAPHICS] .