Abstract: A biomass fuel combustor for use in the pressurized combustion comprising of biomass fule particles to produce a pressurized exhaust gas, the combustor comprising: a cyclonic combustion chamber having a combustion region and first and second fuel inlets, the first inlet being for the entry into the chamber of gas and/or liquid secondary fuel for combustion in said combustion region and the second inlet being for the entry into the chamber of biomass fuel particles also for combustion in said combustion region, the chamber being so constructed and arranged that the heat generated by the secondary fuel combustion will, in use and at least during stan-up of the combustor, promote fragmentation of the incoming biomass fuel particles.