A rich Green River Formation oil shale and derived materials have been subjected to solvent swelling and to radical-forming reagents. Some of the reacted shales from these experiments have been studied using Carbon-13 Nuclear Magnetic Resonance Spectroscopy. Data from swelling experiments indicate the existence of a three-dimensional organic matrix. The reaction of the shale organic matter with radical-forming reagents occurs under certain conditions, but does not result in large increases of bitumen yield. NMR studies indicate that some carbon-heteroatom bonds in the shale may be preferentially attacked by radical-forming species. One reagent may suppress coke formation when heated with shales. The attack by radicals on chemical bonds at kerogen-mineral interfaces could not be confirmed by the experimental data from this preliminary study.