The　synthesis　of　uniform　MnCo2O4　microspheres　and　their　cooperation　with　a　visible　light　harvester　to　achieve　efficient　photocatalytic　CO2　reduction　under　ambient　conditions　are　reported　here.　The　MnCo2O4　materials　were　prepared　by　a　facile　two-step　solvothermal-calcination　method　and　were　characterized　by　XRD,　SEM,　TEM,　EDX,　XPS,　elemental　mapping,　and　N2　adsorption　measurements.　By　using　the　MnCo2O4　microspheres　as　a　heterogeneous　cocatalyst,　the　photocatalytic　performance　of　the　CO2-to-CO　conversion　catalysis　was　remarkably　enhanced,　and　no　decrease　in　the　promotional　effect　of　the　cocatalyst　was　observed　after　repeatedly　operating　the　reaction　for　six　cycles.　13CO2　isotope　tracer　experiments　verified　that　the　CO　product　originated　from　the　CO2　reactant.　The　effect　of　synthetic　conditions　and　various　reaction　parameters　on　the　photocatalytic　activity　of　the　system　were　investigated　and　optimized.　The　stability　of　the　MnCo2O4　cocatalyst　in　the　CO2　reduction　system　was　confirmed　by　several　techniques.　Moreover,　a　possible　mechanism　for　MnCo2O4-cocatalyzed　CO2　photoreduction　catalysis　is　proposed.　©　2015　American　Chemical　Society.