The purpose of this project was to obtain information on the high-temperature retorting of oil shale in a single-vessel fluidized bed under conditions that would give maximum production of benzene. In order to obtain the necessary retorting temperatures of 1500supO to 18oosupO/F. with a two-vessel fluidized retort, a large recycle ratio of hot, burnt shale to raw shale feed would be needed. With a single vessel, there seemed to be the possibility that the coke on the spent shale could be burned in the lower part of the fluidized bed, thus supplying the heat needed to obtain the desired high retorting temperatures. At these temperatures, the rate of heating and retorting of pulverized shale is in the order of a second. This is a short enough time, supposedly, for the shale to be retorted in the upper part of the fluidized bed by contact with hot, burnt shale, before being carried by thermal solids circulation, into contact with oxygen in the entering fluidizing gas.