Midway Sunset crude oil and well-head oil were treated at elevated temperatures in a closed system with the presence of water. Mild to moderate upgrading, as measured by increase in API gravity, was observed at 400°C or above. Reduced pressure operation exhibited upgrading activity comparable to upgrading under normal aqueous pyrolysis conditions. Reduced pressure operation was obtained by the use of specific blending methods, a surfactant, and the proper amount of water. The use of metal complexes provided additional upgrading. The best of the minimum set tested was Co(ll) 2-ethylhexanoate. Fe, Zn, Mo, Cu, and Ni complexes also showed some levels of activity.