With the continuously decreasing quality of crude oils, issues may arise with refining and transporting such oils. New technology must be developed to address these issues. Coupling a thermal cracker with a catalytic cracker in series was investigated as a possible method of directly treating heavy fractions as well as paraffinic whole crude oils. A potential application of this cracker configuration would be upstream treatment ofhigh pour point crudes to improve flowability. The idea was to deposit a fraction of the coke on the thermal medium that would otherwise be deposited on the catalyst, thereby extending the life of the catalyst. This concept was tested using two transport reactors, one with sand and the other with catalyst, and with three feedstocks, atmospheric residuals, fluid catalytic cracker feed, and a waxy crude oil. Product distributions were determined for variations in thermal and catalytic cracker residence times, cracker temperatures, feedstock type, and catalyst/oil ratios. The data gathered show that coupling a thermal and a catalytic cracker may provide some definite advantages. The typical liquid yields for the combined thermal and catalytic cracker ranged from around 50 to 75%. One of the experiments produced a bimodal distribution of hydrocarbons in the liquid products, with the first distribution being olefinic and the second distribution being paraffinic, with a 68.4% liquid yield. Promising results were obtained with a waxy crude oil, wherein 34.6% by weight of the liquid products was naphtha.