The Bureau of Mines heated Green River oil shale that had been previously extracted by benzene to provide information on in situ processing conditions, to determine the effect of low temperature heating on the unconverted kerogen, and to determine the composition of benzene-soluble thermal products. Tests were conducted at 150 deg to 350 deg c for 0.5 to 360 days. In general, it was concluded that significant increases in the degradation of kerogen to oil occurred between the temperature range of 250 deg to 350 deg c; that the composition of the soluble products depends upon the temperature at which they are formed; and that the n-alkanes are pyrolytically degraded from the kerogen structure. In particular, the 250 deg c heating temperature is beneficial to the formation of branched plus cyclic alkanes. Also, the heated and unconverted oil shale kerogen and the soluble thermal products become more aromatic as the temperature increases from 150 deg to 350 deg c. Work done in cooperation with the University of Wyoming.