A process for the thermal conversion of the organic component associated with tar sands to lower boiling, higher value products. The conversion is achieved by subjecting the organic component containing from about 1 to 20 wt. % native solids to elevated temperatures and pressures. Compared to conventional thermal conversion processes, such as visbreaking, much higher conversion of the organic component can be achieved owing to the presence of native solids on which coke is deposited instead of fouling the process equipment. This higher conversion is also associated with enhanced removal of sulfur and metals.