Fuel cells are efficient electrochemical devices with wide applications, from portable power to stationary generation. They are categorized by operating temperature: low ( <100°C), intermediate (450-800°C), and high (>800°C). Recent attention has focused on reduced-temperature fuel cells (200-400°C) due to their benefits. A fuel cell consists of a porous anode, dense electrolyte, and porous cathode, each requiring specific materials for conductivity, stability, and thermal expansion. This article reviews challenges and recent advances in anode, electrolyte, and cathode materials for various fuel cells, including those operating at 200-400°C. It also outlines key research areas and opportunities. Fuel cells are crucial for a carbon-neutral society, replacing fossil fuels. They offer high efficiency and low emissions, with potential applications from small devices to large power generation. A complete fuel-cell system includes cell stacks, gas delivery, thermal management, and electrical control components. Each cell has a porous cathode and anode with a dense electrolyte, where oxygen reduction occurs at the cathode and fuel oxidation at the anode. Electrodes must be porous, catalytically active, and conductive, while the electrolyte must be dense and conductive to prevent fuel mixing. Different fuel cells have distinct applications and are categorized by operating temperature, ionic conduction mechanism, or fuel type. Common electrolyte types include oxygen ion (SOFCs), proton (PEMFCs), protonic ceramic (PCFCs), solid acid (SAFCs), carbonate (MCFCs), and anion exchange membrane (AEMFCs). Low-temperature fuel cells require precious metal catalysts, while intermediate and high-temperature fuel cells offer broader material options but face sealing and thermal management challenges. PEMFCs and SOFCs are the most mature, with efforts to improve performance through higher operating temperatures and lower costs. Electrolytes must be dense and conductive, with high ionic conductivity at target temperatures. Doped ceria is suitable for temperatures below 650°C, while Bi₂O₃-based electrolytes face instability in reducing atmospheres. Electrolyte membranes must also have sufficient mechanical strength and compatibility with other cell components. Cathodes require high ORR activity and durability, with materials like perovskite oxides (LSCF, LSM) showing high electronic conductivity. However, they must resist impurities and maintain stability. Anodes must have high electrocatalytic activity and electronic conductivity, with carbon-based materials suitable for low-temperature fuel cells but less stable at higher temperatures. Anode materials must also resist poisoning and maintain redox stability. Recent advances in fuel-cell materials include low-temperature polymer-exchange membranes (PEMs and AEMs), with PEMs using PFSA-based membranes and AEMs showing improved stability. AEMFuel cells are efficient electrochemical devices with wide applications, from portable power to stationary generation. They are categorized by operating temperature: low ( <100°C), intermediate (450-800°C), and high (>800°C). Recent attention has focused on reduced-temperature fuel cells (200-400°C) due to their benefits. A fuel cell consists of a porous anode, dense electrolyte, and porous cathode, each requiring specific materials for conductivity, stability, and thermal expansion. This article reviews challenges and recent advances in anode, electrolyte, and cathode materials for various fuel cells, including those operating at 200-400°C. It also outlines key research areas and opportunities. Fuel cells are crucial for a carbon-neutral society, replacing fossil fuels. They offer high efficiency and low emissions, with potential applications from small devices to large power generation. A complete fuel-cell system includes cell stacks, gas delivery, thermal management, and electrical control components. Each cell has a porous cathode and anode with a dense electrolyte, where oxygen reduction occurs at the cathode and fuel oxidation at the anode. Electrodes must be porous, catalytically active, and conductive, while the electrolyte must be dense and conductive to prevent fuel mixing. Different fuel cells have distinct applications and are categorized by operating temperature, ionic conduction mechanism, or fuel type. Common electrolyte types include oxygen ion (SOFCs), proton (PEMFCs), protonic ceramic (PCFCs), solid acid (SAFCs), carbonate (MCFCs), and anion exchange membrane (AEMFCs). Low-temperature fuel cells require precious metal catalysts, while intermediate and high-temperature fuel cells offer broader material options but face sealing and thermal management challenges. PEMFCs and SOFCs are the most mature, with efforts to improve performance through higher operating temperatures and lower costs. Electrolytes must be dense and conductive, with high ionic conductivity at target temperatures. Doped ceria is suitable for temperatures below 650°C, while Bi₂O₃-based electrolytes face instability in reducing atmospheres. Electrolyte membranes must also have sufficient mechanical strength and compatibility with other cell components. Cathodes require high ORR activity and durability, with materials like perovskite oxides (LSCF, LSM) showing high electronic conductivity. However, they must resist impurities and maintain stability. Anodes must have high electrocatalytic activity and electronic conductivity, with carbon-based materials suitable for low-temperature fuel cells but less stable at higher temperatures. Anode materials must also resist poisoning and maintain redox stability. Recent advances in fuel-cell materials include low-temperature polymer-exchange membranes (PEMs and AEMs), with PEMs using PFSA-based membranes and AEMs showing improved stability. AEM