Structural, electronic, thermochemical and electrical properties of mono-, di- and trihalomethylpyrroles (HMPys), NC 4 H 4 –CH n X 3−n ; X=F, Cl, Br; n=0, 1, 2, 3, and their radical cations have been studied using DFT-B3LYP method with 6-31G(d,p) basis set. Vibrational frequencies and NMR shielding constants of these compounds have also been calculated and analyzed. HMPys are proposed in this research as candidate monomers for conducting polymers with modified characteristics compared to polypyrrole and polymethylpyrrole. Stability of HMPy radical cations have been studied in detail and compared with available experimental data, including oxidation potentials. Results of the present study show that bromomethylpyrroles have the highest thermochemical stability and have higher characteristics for electropolymerization compared to fluoro- and chloromethylpyrroles. Stability of HMPys increases with increasing number of substituted halogen atoms.