This study reports the synthesis and superconductivity of yttrium-cerium hydrides under high pressure. Researchers synthesized yttrium-cerium alloy hydrides through seven independent experiments, using ammonia borane as a hydrogen source and pressure transmitting medium. The synthesized samples exhibited superconductivity with onset critical temperatures ranging from 97 to 141 K. The upper critical field at 0 K was determined to be between 56 and 78 T at 124 GPa. Structural analysis and theoretical calculations confirmed that the hexagonal phase of Y0.5Ce0.5H9 with space group P63/mmc is stable under the studied pressure range. These results indicate that alloying superhydrides can maintain relatively high critical temperatures at modest pressures accessible by laboratory conditions. Rare earth hydrides have shown potential for near-room temperature superconductivity due to chemical pre-compression from hydrogen and tetragen atoms. Yttrium hydrides have also been studied for their high critical temperatures. Cerium superhydrides can be stabilized at low pressures but can also be superconductive. The enhanced chemical pre-compression in CeH9 is attributed to the delocalized nature of Ce 4f electrons. Recent studies have found superconductivity in cerium superhydrides with critical temperatures up to 115 K at 95 GPa and 57 K at 88 GPa. The exploration of high-temperature superconductivity in superhydrides at low pressures or ambient pressure is highly desired. Ternary alloy hydrides offer diverse chemical compositions and structures, providing advantages of different elements. Lanthanum-yttrium ternary hydrides have shown superconductivity with a maximum critical temperature of 253 K at pressures of 170-196 GPa. Lanthanum-cerium ternary superhydrides have shown superconductivity with a critical temperature of ~176 K at -100 GPa. Theoretical calculations suggest that ternary superhydrides can maintain high critical temperatures at relatively low pressures. The study synthesized Y0.5Ce0.5 hydrides using a diamond-anvil cell and laser heating. The samples showed superconductivity with critical temperatures ranging from 97 to 141 K. Electrical transport measurements showed superconducting transitions at various pressures. The upper critical field was determined to be between 56 and 78 T at 124 GPa. Structural characterization using synchrotron XRD confirmed the hexagonal phase of Y0.5Ce0.5H9 with space group P63/mmc. Theoretical calculations showed that the phase is stable under the studied pressure range. The study demonstrates that alloying superhydrides can achieve high critical temperatures at modest pressures, offering a promisingThis study reports the synthesis and superconductivity of yttrium-cerium hydrides under high pressure. Researchers synthesized yttrium-cerium alloy hydrides through seven independent experiments, using ammonia borane as a hydrogen source and pressure transmitting medium. The synthesized samples exhibited superconductivity with onset critical temperatures ranging from 97 to 141 K. The upper critical field at 0 K was determined to be between 56 and 78 T at 124 GPa. Structural analysis and theoretical calculations confirmed that the hexagonal phase of Y0.5Ce0.5H9 with space group P63/mmc is stable under the studied pressure range. These results indicate that alloying superhydrides can maintain relatively high critical temperatures at modest pressures accessible by laboratory conditions. Rare earth hydrides have shown potential for near-room temperature superconductivity due to chemical pre-compression from hydrogen and tetragen atoms. Yttrium hydrides have also been studied for their high critical temperatures. Cerium superhydrides can be stabilized at low pressures but can also be superconductive. The enhanced chemical pre-compression in CeH9 is attributed to the delocalized nature of Ce 4f electrons. Recent studies have found superconductivity in cerium superhydrides with critical temperatures up to 115 K at 95 GPa and 57 K at 88 GPa. The exploration of high-temperature superconductivity in superhydrides at low pressures or ambient pressure is highly desired. Ternary alloy hydrides offer diverse chemical compositions and structures, providing advantages of different elements. Lanthanum-yttrium ternary hydrides have shown superconductivity with a maximum critical temperature of 253 K at pressures of 170-196 GPa. Lanthanum-cerium ternary superhydrides have shown superconductivity with a critical temperature of ~176 K at -100 GPa. Theoretical calculations suggest that ternary superhydrides can maintain high critical temperatures at relatively low pressures. The study synthesized Y0.5Ce0.5 hydrides using a diamond-anvil cell and laser heating. The samples showed superconductivity with critical temperatures ranging from 97 to 141 K. Electrical transport measurements showed superconducting transitions at various pressures. The upper critical field was determined to be between 56 and 78 T at 124 GPa. Structural characterization using synchrotron XRD confirmed the hexagonal phase of Y0.5Ce0.5H9 with space group P63/mmc. Theoretical calculations showed that the phase is stable under the studied pressure range. The study demonstrates that alloying superhydrides can achieve high critical temperatures at modest pressures, offering a promising