This publication contains the latest information on coated particle fuel technologies and may be used as a baseline reference to support the fuel technologies of high temperature gas-cooled reactor (HTGR) small modular reactors (SMRs). The HTGR concept is considered a promising nuclear reactor technology due to its inherent safety and operational features. A typical example of its unique core design is the inert, single-phase coolant (helium gas) coupled with a high-temperature, high-heat capacity moderator (graphite), which allows for a greater response time to core heat up accidents. As HTGRs have the potential to supply high temperature process heat, many other applications such as hydrogen production and electricity generation are also viable. Coated particle fuel technology research programmes have been pursued in several Member States, including the design, manufacturing, characterization, irradiation behaviour and behaviour prediction, accident tests and simulations. This TECDOC is a resource for researchers and for nuclear power plant engineers and operators, fuel technology engineers and designers, and material science engineers.