The field emission characteristics of an oxidized porous polysilicon were investigated using different oxidation process with Pt=Ti multi layer electrode. The surface oxidation layer on an oxidized porous polysilicon was formed by thermal oxidation and electrochemical oxidation. The emission efficiency of thermal oxidation which was performed in a dry O 2 with O 2 flow rate of 3 l=min at 900 C for 60 min showed 3.36% at V ps ¼ 16 V. The electrochemical oxidation was formed by solution containing 1 M sulphuric acid under 10 mA=cm 2 for 40 sec and was annealed 5 hr to improve oxide quality at 600 C. The emission efficiency of electrochemical oxidation showed 3.81% at V ps ¼ 14 V.