Less conventional sources of hydrocarbon feedstocks such as oil sands, tar sands and shale oils are being exploited. These feedstocks generate a larger amount of heavy oil, gas oil, asphaltene products and the like containing multiple fused aromatic ring compounds. These multiple fused aromatic ring compounds can be converted into feed for a hydrocarbon cracker by first hydrogenating at least one ring in the compounds and subjecting the resulting compound to a ring opening and cleavage reaction. The resulting product comprises lower paraffins suitable for feed to a cracker, higher paraffins suitable for example as a gasoline fraction and mono aromatic ring compounds (e.g. BTX) that may be further treated.