Ethylene evolved in fruit storage must be removed to delay their softening. Complete oxidation of ethylene was studied over supported metal or metal oxide catalysts, especially highly dispersed Au/Al2O3 and Au/Co3O4. The ethylene over all catalysts, was completely oxidized to produce only CO2 and water. Among metal oxide catalysts, Mo, Cr, and Mn oxides showed the highest activity. The activity of gold catalysts was much higher than that of metal oxide catalysts. The activity order of gold catalysts prepared by different method was DP>CP>IP. Gold particle on Co3O4 was more active than that on Al2O3. It was therefore considered that gold particles promote dissociative adsorption of oxygen which reacts with ethylene adsorbed on support adjacent to active site. It was known that ultra-fine gold particle oxidized completely ethylene even at relatively low temperature and concentration.