The structures of 1,7-dimethyl-1,7-bis(dichloromethyl)-5,8-ethenodecalin-3-ene-2,6-dione, the dimer of 6-methyl-6-dichloromethyl-cyclohexa-2,4-dien-1-one, and of products of its bromination were established by XRD analysis. The dependence of composition of the products of bromination on the ratio of reactants was established. Electrochemical reduction of the dione and its bromine-containing derivatives was studied.