A basic understanding of cataytic microreversibility described below has led to the further development of the concept of catalytic coking. In this concept, a catalyst, such as MoS2, which, under high hydrogen pressure and temperature, puts an extensive amount of hydrogen into petroleum molecules, whereas under the low pressure of hydrogen, the catalyst redistributes the hydrogen, thus rejecting asphaltenes and other heavy molecules as coke. This results in a clean liquid product as the heavy molecules are rejected. MoS2 is a layered transition-metal sulfide catalytic material well-known in the refining industry. Upgrading tests on samples of Cold Lake bitumen were carried out using transition-metal sulfide (TMS) nanoparticle catalysts in a special-purpose batch reactor. The tests covered a range of process temperatures and catalyst concentrations in order to explore the broad effects of catalyst performance. Typical reactor process conditions were 400-450 degrees C for periods of up to 1 h, with catalyst weight concentrations ranging from similar to 0.2% to just under 1.0%. All tests were conducted at ambient pressure in a hydrogen atmosphere. Results show an upgrading of similar to 80 wt % of the bitumen to a liquid product typically in the range of 21 API (American Petroleum Institute viscosity index), having a viscosity of similar to 7-9 cP, using as little as 0.23 wt % catalyst. The remaining solid coke product is largely carbon, with the addition of most of the original trace heavy metals, and the catalyst.