Mono-olefins produced in the process of pyrolysis of the hydrocarbon feedstock are one of the main sources for petrochemical synthesis, that accounts for the importance of searching for methods to improve the process. The aim of the work is to develop a method for increasing efficiency of the pyrolysis process on the basis of the allene effect on thermal decomposition of hydrocarbons, which are the pyrolysis feedstock constituents and also form in the process. Effect of the allene addition on thermal decomposition of hexene-1, hexane and gasoline fraction of oil was studied. It was shown that in the presence of allene the rate of thermal decomposition of hydrocarbons significantly increases. Carrying out the pyrolysis process in the presence of allene additionves allows one to lower the temperature of the process at a given time or the reaction time at a given temperature. ; ACKNOWLEDGEMENT This research was supported by Act 211 Government of the Russian Federation, contract № 02. A03.21.0006.