A　formaldehyde-phosphomolybdic　acid　battery　is　designed　to　simultaneously　achieve　the　production　of　reduced　phosphomolybdic　acid　with　electricity　and　hydrogen　generation,　in　which　CuxO　nanowire　arrays　in-situ　grown　on　Cu　foam　is　used　as　an　efficient　porous　electrode　for　the　H2　production　from　the　electrooxidation　of　formaldehyde.　And　the　reduced　polyoxometalate　can　further　act　as　an　electron-coupled　proton　buffer　for　the　decoupled　hydrogen　production　from　water　electrolysis.　The　reported　battery　possesses　an　open　circuit　voltage　of　about　0.95　V　with　a　peak　power　density　of　8.0　mW　cm−2.　Multiple　discharge　experiments　reveal　that　the　Faradaic　efficiency　for　the　hydrogen　production　from　anodic　formaldehyde　oxidation　is　sustained　at　∼100%,　and　a　repeatable　current　density　curve　of　the　hydrogen　production　with　a　theoretical　maximum　coulombic　efficiency　of　100%　can　be　achieved　by　oxidizing　the　reduced　phosphomolybdic　acid,　suggesting　a　good　stability　of　the　reported　cell　device　for　dual-decoupled　hydrogen　production.　©　2024　Hydrogen　Energy　Publications　LLC