The　development　of　highly　efficient　electrocatalysts　has　attracted　increasing　attention　in　the　field　of　electrochemical　energy　conversion.　Therefore,　we　report　a　simple　self-template　method　to　construct　Co-Sn-X　(X　=　S,　Se,　Te)　nanocages　through　the　anion　exchange　reaction　of　CoSn(OH)6　nanocubes　with　chalcogenide　ions　under　mild　solvothermal　conditions.　Benefiting　from　advantageous　compositional　features　and　well-designed　architectures,　the　obtained　Co-Sn-X　(X　=　S,　Se,　Te)　nanocages　display　enhanced　electrocatalytic　activity　for　dye-sensitized　solar　cells　(DSSCs)　and　the　oxygen　evolution　reaction　(OER)　in　an　alkaline　electrolyte.　Remarkably,　the　Co-Sn-Se　nanocages　as　the　counter　electrode　(CE)　catalyst　deliver　a　prominent　power　conversion　efficiency　(PCE)　of　9.25%　for　DSSCs　compared　with　Pt　CE　(8.19%).　Furthermore,　when　used　as　an　OER　catalyst,　the　Co-Sn-Se　nanocages　also　exhibit　outstanding　electrocatalytic　activity　in　terms　of　their　low　overpotential　of　304　mV　at　the　current　density　of　10　mA　cm-2　and　long-term　stability　in　1.0　M　KOH　solution.　This　work　provides　wide　prospects　for　the　rational　design　and　synthesis　of　high-performance　transition　metal　chalcogenide-based　electrocatalysts　for　future　energy　conversion　systems.　©　2018　The　Royal　Society　of　Chemistry.