<p>Pyroprocessing is a promising technology for recycling spent nuclear fuel due to its compact system design, high tolerance to radiation and heat, and inherent resistance to nuclear proliferation. However, thermal treatment of spent fuel during the process results in the release of gaseous fission products, which must be managed to ensure environmental safety and regulatory compliance. In contrast to aqueous reprocessing, where many fission products remain in solution, pyroprocessing involves direct high-temperature volatilization of radionuclides, resulting in distinct release behaviors that require tailored management. This review provides an overview of the off-gas behavior of key fission products such as Cs-137, I-129, Tc-99, Se-79, H-3, C-14, and Kr-85 during the process steps, including voloxidation and sintering. The release characteristics are analyzed with respect to their chemical forms, thermal stability, and sensitivity to process conditions. The recent advances in capture technologies are also reviewed, focusing on materials and methods applicable to the pyrochemical environment. These include both conventional and emerging strategies for selective capture and immobilization of radioactive gases. By integrating findings from thermodynamic and experimental studies, this review highlights critical considerations for designing efficient off-gas treatment systems in pyroprocessing, providing guidance for future development of sustainable radionuclide management.</p>