This work presents the dynamic behaviour of a new recuperated micro gas turbine (mGT) coupled with a large volume. Such system, called “emulator”, has been purposely designed for the future upgrade into a fuel cell mGT hybrid system. The tests, carried out by LG Fuel Cell Systems (LGFCS), aimed both at understanding the dynamic behaviour of the system and validating the dynamic simulation tool.Within the wide experimental campaign, a subset of data has been selected to identify the key transient phenomena and characterise the dynamic behaviour of the system: in this respect, the focus is on start-up, warm-up and shutdown phases.A dynamic model of the emulator was developed, based on the original software TRANSEO. The model was used to characterise the mGT performance and identify a performance gap in the expander. For this purpose, the machine was upgraded and substituted. Final results show that, after refinement of input data, the model is capable to predict accurately the overall system transient behaviour.