Abstract：A summary is given on the history of development of fluidized bed conversion (combustion and gasification) of solid fuels. It first includes gasification, following a line of development from the Winkler gasifier until the most recent designs. In addition to pulverized combustors, the most important fuel converters for combustion of solid fuel are circulating fluidized bed (CFB) boilers, whose design is becoming mature and the increment in size is the presently most important task. The very new aspects of these conversion devices are related to CO2 removal. Methods with this purpose involving fluidized bed (oxyfuel combustion, chemical looping combustion, and calcium looping cycle) are briefly surveyed with emphasis on CFB. The last two types of plant consist of twin fluidized-bed also called dual fluidized-bed. This group of devices also includes indirect gasifiers.