Abstract: A process for preheating oil shale in which the oil shale is partially preheated to 200.degree. F. to 400.degree. F. in a first lift pipe followed by final preheat to temperatures of between 400.degree. F. and 650.degree. F. in a second lift pipe. Hydrocarbons released from the oil shale in both the first and second lift pipes are incinerated in an incinerator/recuperator. In order to provide adequate incineration and combustion of the hydrocarbons released in the first, low temperature lift pipe, the entrainment gas or first gas stream is a low Btu gas preferably produced from conventional gasification of carbonaceous material. The low Btu entrainment gas along with released hydrocarbons is utilized as a fuel in the incinerator/recuperator and also may be utilized for other combustion applications in oil shale pyrolysis processing. In oil shale pyrolysis carried out with ceramic balls as heat exchange bodies, a portion of the low Btu entrainment gas is conveniently utilized to fuel the ball heater.