The thermolysis of hexachlorane in a flowing precipitator system in an inert gas atmosphere was studied. To process the obtained kinetic data a stationary model of a piston reactor with an arbitrary number of sequential and parallel heterogeneous reactions proceeding in a mixed diffusion-kinetic regime was used. Based on the results of the solution of the inverse problem the mechanism of the process and its kinetic parameters have been established. The results of the work can be used in the reprocessing of obsolete and banned pesticide preparations.