Catalytic water gas shift for hydrogen production in the temperature range of 423-873 K, was examined imposing an electric field to the catalyst bed. Reaction trends were investigated based on thermodynamic equilibrium and chemical kinetic law. Pt/La-ZrO2 was chosen as an active catalyst through our screening tests, and the effect of the electric field on the catalytic activity was investigated by changing reaction temperatures and applied electric currents. Although the reaction was ruled by thermodynamic equilibrium at high temperatures, drastic promotion of the reaction by applying the electric field was observed at low temperatures in a kinetic region. Drastic decrease of apparent activation energy for WGS was observed by imposing the electric field to the catalyst bed. Various isotopic transient tests revealed that the reaction mechanism changed by the application of electric field, and redox mechanism using surface lattice oxygen played an important role in case of the catalytic WGS in the electric field. [GRAPHICS]