Abstract: There is disclosed a method of operating a gas turbine engine of a type having a compressor section, a combustor section, and a turbine section arranged in flow series. The method involves the steps of: providing a supply of cryogenic liquid fuel; vaporising the cryogenic liquid fuel to produce a gaseous fuel; expanding said gaseous fuel in at least one fuel turbine external to the engine's turbine section; and thereafter directing said expanded gaseous fuel into the engine's combustion section for combustion therein. A related gas turbine arrangement configured for implementation of the method is also disclosed.