[en] The 'Atoms for Peace' mission initiated in the mid-1950s paved the way for the development and deployment of nuclear fission reactors as a source of heat energy for electricity generation in nuclear power reactors and as a source of neutrons in non-power reactors for research, materials irradiation, and testing and production of radioisotopes. The fuels for nuclear reactors are manufactured from natural uranium (∼99.3% ²³⁸U + ∼0.7% ²³⁵U) and natural thorium (∼100% ²³²Th) resources. Currently, most power and research reactors use ²³⁵U, the only fissile isotope found in nature, as fuel. The fertile isotopes ²³⁸U and ²³²Th are transmuted in the reactor to human-made ²³⁹Pu and ²³³U fissile isotopes, respectively. Likewise, minor actinides (MA) (Np, Am and Cm) and other plutonium isotopes are also formed by a series of neutron capture reactions with ²³⁸U and ²³⁵U. Long term sustainability of nuclear power will depend to a great extent on the efficient, safe and secure utilization of fissile and fertile materials. Light water reactors (LWRs) account for more than 82% of the operating reactors, followed by pressurized heavy water reactors (PHWRs), which constitute ∼10% of reactors. LWRs will continue to dominate the nuclear power market for several decades, as long as economically viable natural uranium resources are available. Currently, the plutonium obtained from spent nuclear fuel is subjected to mono recycling in LWRs as uranium-plutonium mixed oxide (MOX), containing up to 12% PuO₂, in a very limited way. The reprocessed uranium (RepU) is also re-enriched and recycled in LWRs in a few countries. Unfortunately, the utilization of natural uranium resources in thermal neutron reactors is <1%, even after recycling of Pu and RepU. UO₂ and MOX fuel technology has matured during the past five decades. These fuels are now being manufactured, used and reprocessed on an industrial scale. Mixed uranium- plutonium monocarbide (MC), mononitride (MN) and U-Pu-Zr alloys are recognized as advanced fuels for sodium cooled fast reactors (SFRs) on the basis of their higher breeding ratio and higher thermal conductivity. The advanced SFR fuels have so far been prepared only on a pilot plant scale in a very few countries, and MA bearing metal, oxide, carbide, nitride and inert matrix fuels are being prepared only on a laboratory scale for property evaluation and irradiation testing. Likewise, thorium based MOX has been manufactured on a pilot plant scale and utilized in power reactors in a few countries in a limited way, but there is no industrial facility for manufacturing these fuels. Until the end of the 1970s, non-power research reactors and their fuels were mostly supplied worldwide by the USA and the former USSR. These reactors used high enriched uranium (HEU) fuel, containing >80% ²³⁵U in the form of aluminium matrix, UAl_x or U3O₈ dispersion fuel of low uranium density (1.3-1.7 g/cm³). In 1978, the USA launched the Reduced Enrichment for Research and Test Reactors (RERTR) Programme, with the objective of converting the HEU core to a low enriched uranium (LEU) core without affecting the operation and performance of the reactors. Later, the Russian Federation also joined this programme. As part of this programme, LEU based Al-U₃Si₂ dispersion fuel with a uranium density of 4.8 g/cm³ emerged and has been qualified. Efforts are under way to develop advanced fuels such as U-Mo alloy either as Al matrix dispersion fuel with a density of 6-8.5 g/cm³ or as monolithic fuel with a uranium density of 15-16 g/cm³. The IAEA has been fostering information exchange and collaborative R and D among Member States for the development, manufacture and performance evaluation of nuclear fuels for both nuclear power and research reactors, and has published a number of technical reports on nuclear fuels. The purpose of this report is to summarize the current status of nuclear fuel manufacturing technology worldwide for both power reactors and research reactors, and to highlight the trends that are emerging for advanced fuels.