A bench scale (1 1/2" diameter) fluid bed retort was used to evaluate the effect of rapid heating combined with high sweep gas velocities on product yield from Kentucky oil shale. Emphasis was placed on product collection and material balance cloaure. Distribution of organic carbon among spent shale oil and gas was also examined. Spent shale was used to compare coke formation in the fluid bed as compared to bench scale fixed bed retorting. At a bed temperature of 550 C and 28 L/min helium fluidizing gas velocity, oil yields, based on product collected, were 135-155% (by weight) of Fischer Assay oil yields. Under these conditions, 55% of the raw shal3e organic carbon was removed. Material balances were 100 -.1% For the same shale a decrease in non-condensable gases to half that obtained by Fischer Assay, was coupled with the substantial increase in oil weight recovered. This plus a small decreaw3 in fixed carbon in the spent shale, shows a decreased in coke formation in the fluid bed retort in comparison to the fixed bed retort where fixed carbon is formed in the spent shale during retorting. The effect if bed temperature on product yield and distribution was also studied.