Chemical　synthesis　of　unconventional　topologically　close-packed　intermetallic　nanocrystals　(NCs)　remains　a　considerable　challenge　due　to　the　limitation　of　large　volume　asymmetry　between　the　components.　Here,　a　series　of　unconventional　intermetallic　Frank-Kasper　C15　phase　Ir2M　(M　=　rare　earth　metals　La,　Ce,　Gd,　Tb,　Tm)　NCs　is　successfully　prepared　via　a　molten-salt　assisted　reduction　method　as　efficient　electrocatalysts　for　hydrogen　evolution　reaction　(HER).　Compared　to　the　disordered　counterpart　(A1-Ir2Ce),　C15-Ir2Ce　features　higher　Ir-Ce　coordination　number　that　leads　to　an　electron-rich　environment　for　Ir　sites.　The　C15-Ir2Ce　catalyst　exhibits　excellent　and　pH-universal　HER　activity　and　requires　only　9,　16,　and　27　mV　overpotentials　to　attain　10　mA　cm-2　in　acidic,　alkaline,　and　neutral　electrolytes,　respectively,　representing　one　of　the　best　HER　electrocatalysts　ever　reported.　In　a　proton　exchange　membrane　water　electrolyzer,　the　C15-Ir2Ce　cathode　achieves　an　industrial-scale　current　density　of　1　A　cm-2　with　a　remarkably　low　cell　voltage　of　1.7　V　at　80　degrees　C　and　can　operate　stably　for　1000　h　with　a　sluggish　voltage　decay　rate　of　50　mu　V　h-1.　Theoretical　investigations　reveal　that　the　electron-rich　Ir　sites　intensify　the　polarization　of　*H2O　intermediate　on　C15-Ir2Ce,　thus　lowering　the　energy　barrier　of　the　water　dissociation　and　facilitating　the　HER　kinetics.　A　series　of　unconventional　Frank-Kasper　intermetallic　C15-Ir2M　(M　=　rare　earth　metals)　nanocrystals　is　prepared　as　hydrogen　evolution　electrocatalysts,　which　features　higher　Ir-M　coordination　numbers　and　electron-rich　environment.　The　C15-Ir2Ce/C||IrO2　system　in　a　practical　PEMWE　requires　only　a　cell　voltage　of　1.7　V　to　achieve　the　industrial-scale　current　density　of　1　A　cm-2　and　can　keep　stable　for　1000　h　at　80　degrees　C.　image