A process for thermochemical conversion of heavy oil and petroleum coke to fluid fuels includes the steps of: providing a fossil fuel selected from the group consisting of heavy oil, petroleum coke and mixtures thereof; and exposing the fossil fuel to an external source of concentrated radiation so as to increase the temperature of the fossil fuel, supply high-temperature heat required for the desired endothermic conversion process, and convert the fossil fuel to a product selected from the group consisting of hydrogen, carbon monoxide, gaseous hydrocarbons and mixtures thereof.