An object of the present invention is to suppress flooding phenomenon in an electrode catalyst for fuel cells containing a metal atom, a carbon atom, a nitrogen atom and an oxygen atom. A production process of an electrode catalyst for fuel cells is provided which includes a fluorination step of bringing a catalyst body into contact with fluorine, the catalyst body having an atom of at least one metal element selected from the group consisting of zinc, titanium, niobium, zirconium, aluminum, chromium, manganese, iron, cobalt, nickel, copper, strontium, yttrium, tin, tungsten, cerium, samarium and lanthanum, a carbon atom, a nitrogen atom and an oxygen atom.