PURPOSE: To produce a durable electrolytic electrode substrate by forming a binding layer of a partially oxidized material including a substrate metal and a coating layer of the oxide of valve metal successively on the surface of a conductive metallic base material.

CONSTITUTION: The surface of a conductive metallic base material (e.g. titanium and titanium alloy) is roughened to about JIS Ra=10 to 20μm and to about JIS Rmax=50 to 200μm. A spray particle (e.g. Ti and Nb) contg. a metal constituting the base material is thermally sprayed in an oxidizing atmosphere with a gaseous mixture of argon and helium as the plasma gas to form a binding layer (about 10 to 200μm thickness) consisting of a partially oxidized material, and the oxide of valve metal is further sprayed on the binder layer surface to form a coating layer consisting of the oxide. Consequently, a durable electrode substrate sufficiently resistant to electrolysis resulting from positive and negative inversion is obtained.