Results obtained in the studies of gas composition in the hydrocarbon pools of the Jurassic-Cretaceous sediments in the Arctic regions of West Siberia are reported. The specifc features of gas composition in hydrocarbon pools are shown. The main features of the vertical and lateral gas zoning in the Aptian-Albian-Cenomanian, Berriasian-Hauterivian and Jurassic oil and gas bearing complexes are revealed. Generalization of the data on the geochemistry of hydrocarbon gases (the features of component composition, the isotope composition of methane), along with the published data of the geological and geochemical investigation of the Arctic regions of West Siberia, allows us to consider the highly mature Triassic-Middle Jurassic coaly matter as the source of the dry hydrocarbon gases of the Lower and Middle Jurassic complex. Either the Triassic-Middle Jurassic sediments or the Upper Jurassic beds, enriched with the aquatic organic matter, could be involved in the formation of Upper Jurassic and Lower Cretaceous pools. The low-maturity terrestrial (carbonaceous) organic matter of the Cretaceous sediments generated the major amount of light-isotope gases in the Aptian-Albian-Cenomanian sediments. In addition, the source of those gases could be methane formed during oil biodegradation.