CATALYST, ELECTRODE, MEMBRANE ELECTRODE ASSEMBLY, AND AIR BATTERY

Provided is a low-cost catalyst that has excellent oxygen reduction reaction (ORR) catalytic activity and is useful as a catalyst for water electrolysis, an electrode catalyst for an air battery, or the like. The catalyst includes (A) Ni atoms, (B) a condensate of thiourea and formaldehyde, and (C) porous carbon.