In work the impact of ionizing radiation on mixes hexane-hexenе was investigated. Laboratory researches were conducted on a gamma source 60 Co at the power of dose of P=0.10 of Gy / s in intervals of the absorbed doses D=34-103 kGy. Impact of ionizing radiation on structural and group composition of mix hexane-hexene in static conditions was investigated. Density, viscosity, iodic numbers of mixes hexane-hexenе were determined. before radiation at various absorbed doses. Existence of olefin connections is the main reason for small stability in hydrocarbon fuels. Studying of radiolysis of mixes of saturated and nonsaturated hydrocarbons at various concentration gives the chance to draw conclusions about the nature of the main radiochemical processes. In the fuels containing a large amount of nonsaturated hydrocarbons in the course of radiation the coking behavior increases and color worsens. Structuring is physically shown in organic liquids in change of viscosity and density. The processes which arose in connection with radiolysis for a long time develop after the radiation termination that can lead to change of composition of fuel. As a result of it at ambient temperature operational properties of oil fuels worsen. Communication between the chemical composition of fuel and its stability is still insufficiently well studied. These experiments continue for the purpose of studying of impact of ionizing radiation on changes of physical and chemical properties of hydrocarbons of oil.