Subcritical water (SCW) at 400-450 degrees C and 14-21 MPa was used to extract kerogen-derived hydrocarbon material from oil shale. Attention centered on the influence of temperature, pressure, feed particle size, run duration and external hydrogen (from an in situ shift reaction) on yields and compositions of toluene-soluble material. In favorable circumstances, extracts accounted for up to 70% of the precursor organic matter in the shale. H/C ratios ranged to 1.57; carbon aromaticities were as low as 0.35-40; and extraction with SCW in the presence of CO also served to remove most of the sulfur in the source material as H2S. But partially off-setting the high extract yields - which are up to 75% higher than oil yields reportedly obtained from shale retorting - are data that show toluene-solubles generated with SCW or SCW/CO to contain higher proportions of asphaltenes and ＇resins＇ than oils produced by pyrolysis of the shale in corresponding temperature/pressure regimes, and to possess significantly higher molecular weights.