Hybrid dual-fuel combined cycles optimised for energy utilisation of Municipal Solid Waste (MSW) as fuel for heat and power generation can prove to be very competitive in efficiency and economics and easy to control and maintain. The positive effect of adding a gas turbine as a topping cycle to a MSW fired steam boiler has already been pointed out in several publications by different authors. Still more work remains to be done on cycle configuration modelling, performance analysis and wider promotion of such power cycles. This paper aims to assess the performance of MSW and natural gas fired hybrid combined cycles. Three configurations of a natural gas fired gas turbine as a topping cycle and a MSW fired fluidized bed steam boiler as a bottoming cycle have been modelled and analysed. Study of the effects of different gas turbine to MSW boiler power ratios on the optimal cycle configuration and on the efficiency of MSW energy utilisation itself, for each different cycle configuration, is provided. Part-load efficiencies are also investigated.