The invention provides systems and methods for extracting and upgrading heavy hydrocarbons from substrates such as oil sands, oil shales, and tar sands in a unitary operation. The substrate bearing the hydrocarbon is brought into contact with a supercritical or near-supercritical fluid, a source of hydrogen such as hydrogen gas, and a catalyst. The materials are mixed and heated under elevated pressure. As a consequence of the elevated temperature and pressure, upgraded hydrocarbon-containing material is provided in a single or unitary operation. In some embodiments, sonication can be used to improve the upgrading process. Fluids suitable for use in the process include carbon dioxide, hexane, and water. It has been observed that upgrading can occur within periods of time of a few hours.