Abstract: A method of producing pyrolytic oils suitable for petroleum reprocessing is disclosed. According to the invention, petroleum derived organic sludges or oil residues in a solid/liquid phase are subjected to vacuum pyrolysis under temperature and sub-atmospheric pressure conditions such as to prevent gas and vapor phase secondary cracking reactions and to thereby increase the yield of pyrolytic oils to the detriment of hydrocarbon gases. About 97% of the organic matter content of the sludges and about 75% of the organic matter content of the oil residues can be converted into pyrolytic oils suitable for petroleum reprocessing.