We examined oxidative coupling of methane (OCM) and oxidative dehydrogenation of ethane (ODE) over various polyoxometalate supported CeO2 catalysts at 423 K in an electric field. Tetrabutylammonium (TBA) salt of Keggin-type phosphotungstate (PW12O40) supported CeO2 catalysts ((TBA)(3)PW12O40/CeO2) showed high activities for OCM and ODE in the electric field (3 mA) at 423 K, although the catalyst without the electric field showed extremely low activities at such low temperature. FT-IR spectra and XRD patterns confirmed that the structure of (TBA)(3)PW12O40/CeO2 was changed to Ce-2(WO4)(3)/CeO2 after reactions with the electric field, and it acted as an active site structure for OCM and ODE with the electric field. Results of activity tests revealed that the C2H6 production was a main reaction in OCM with the electric field, and C2H4 was formed through a successive oxidative dehydrogenation of the formed C2H6. Periodic operation tests demonstrated that reactive oxygen species suitable for ODE were formed on the catalyst surface of Ce-2(WO4)(3) in the electric field.