Electrochemistry is a useful technique for mild synthesis of poly-mers, but the mechanisms of electrochemical polymerization are challenging to fully understand. Here, we focus on understanding the reaction mechanisms during the electrochemical polymerization of polyhydrocarbons. The overall synthetic pathway for hyper -branched polyhydrocarbons is investigated using electrochemical methods combined with spectroscopy, namely nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR). The oxida-tion and reduction occurring on the anode and cathode are investi-gated by cyclic voltammetry and NMR analyses to distinguish the functions of each electrode at the reaction initiation. Real-time FT -IR measurements during electrochemical polymerization are used to decipher the propagation steps. The termination by various sup-pliers of hydrogen atoms (such as aqueous hydrochloric acid) is examined via NMR spectroscopy using deuterium-labeled acetoni-trile and chloroform. The participation of chlorinated methanes and of the solvent acetonitrile in the electrochemical polymerization is interrogated. Overall, these findings advance understanding of the key steps in the polymerization reaction.