Abstract: A method of and apparatus for recovering oil from solid hydrocarbonaceous terial, such as oil shale, in particulate form using a combustion chamber and a reaction chamber arranged side-by-side and connected by a first passageway extending between the upper regions of the chambers and a return passageway. The particulate material is fluidized in the chambers and induced to circulate therebetween by the configuration of the chambers and passageways and/or the nature of the fluidization. Residual carbon on the spent hydrocarbonaceous material introduced into the combustion chamber through the return passageway is burnt, heating the material which then circulates through the first passageway to mix with and heat fresh feed material introduced into the reaction chamber giving off effluent vapours which are collected and processed.