Comparative study of boron doped micro/nanocrystalline diamond (BDD/BDND) electrodes was performed using electrochemical impedance spectroscopy measurements (EIS). The morphological and structural characterizations of BDD/BDND films were analyzed by scanning electron microscopy and Raman scattering spectroscopy. The films were grown with different boron amounts added in the feed gas. The boron source for BDND was smaller in concentration than that for BDD sample. Nonetheless, differential capacitance (Mott-Schottky plots) and heterogeneous charge transfer constant results showed similar doping level for both electrodes. This behavior indicated the high efficiency to dope nanocrystalline diamond films.