The studies reported in this paper extend the application of sequential simulation to the reliability analysis of composite power systems containing mixed hydrothermal generation. The paper summarises the basic characteristics of sequential simulation. It also summarises the main elements to be considered and modelled for the reliability analysis of these types of systems to jointly account for energy limitations, generation capacity and transmission deficiencies. A composite hydrothermal reliability test system (CHT-RTS) based on the original IEEE reliability test system is used to illustrate the analysis of composite power systems containing mixed hydrothermal generation.