Major changes in oil-refining technologies have occurred over the last few years; the requirements to petroleum product quality and their environmental properties have been raised. Hydrogenation and thermal catalytic processes have been widely implemented, an oil conversion ratio has been rapidly increased, there have been a significant growth in the field of process automation, and the methods of refinery design have been changed. This textbook fills in the resultant gap. It covers a wide range of problems related to oil refining. A wide range of modern basic processes for petroleum feedstock conversion is presented and set forth in layman's terms; the emphasis is on efficient technologies for processing oil residues. The textbook gives sufficiently complete characteristics of the modern oil conversion processes. Particular attention has been paid to process flow diagrams of process units; modes and features of vessel operation were reviewed in detail; chemism and mechanisms of basic reactions are presented for every process. The textbook discusses in detail the issues related to the use of modern catalysts and states the effect of changing the feedstock composition on the catalyst activity. The chapters dealing with the configurations of modern refineries are of considerable interest. The detailed description of off-site facilities is especially noteworthy. This textbook is timely: recently the RF Government has set a task to carry out the speedy modernization of the Russian oil-refining industry aimed at improving the petroleum product quality, in order to bring it up to the European norm requirements and drastically increase the oil conversion ratio. A textbook intended for bachelors, masters, postgraduates, students of petroleum secondary schools, specialists in the field of oil refining and petrochemicals, scientists working at universities and research institutes.