Constructing　heterojunction　interface　as　an　active　catalyst　is　an　effective　strategy　to　boost　electrocatalytic　activity　of　oxygen　evolution　reaction　(OER).　Herein,　we　report　an　interfacial　CoP/CeO2　heterostructure　catalyst　constructed　by　interface　engineering　and　selective　phosphorization　procedure.　X-ray　photoelectron　spectroscopy　(XPS)　suggests　that　coupling　CeO2　nanoparticles　on　the　surface　of　CoP　will　generate　interfacial　interaction　at　the　two-phase　interface,　resulting　in　electron　transfer　between　CoP　and　CeO2　components　at　the　interface.　Benefitting　from　the　interfacial　interaction,　large　exposed　interface　area,　and　luxuriant　mesopores　structure,　CoP/CeO2　shows　fascinating　alkaline　OER　performance.　At　the　current　densities　of　10　and　50　mA　cm−2,　the　optimal　CoP/CeO2　heterojunction　exhibits　lower　overpotential　(257　and　298　mV)　than　either　CoP　(288　and　354　mV)　or　RuO2　(305　and　409　mV).　This　work　provides　a　facile　synthetic　protocol　for　constructing　heterostructure　interfaces　to　improve　OER　performance.　©　2023　Chinese　Society　of　Particuology　and　Institute　of　Process　Engineering,　Chinese　Academy　of　Sciences