Activation of heavy hydrocarbon feeds, preferably by thermal treatment, improves downstream catalytic processing. One embodiment of such thermal treatment is shown in figure 2. A hydrocarbon resid (209) is first pretreated in a microwave heater (211). The pretreated resid is then admixed with catalyst and light hydrocarbons wherein the mixture is passed up through a riser reactor (206). In the riser reactor the pretreated resid is catalytically cracked. Another mode of thermal pretreatment of the hydrocarbon feed is visbreaking. This is shown in figure 4.
