Boron-doped diamond has been deposited over a Mo substrate by microwave plasma CVD using methane and hydrogen. Boron doping of diamond has been achieved in situ by using a solid boron source while growing the diamond. Impedance spectroscopy of diamond in 0.5 M NaCl solution has been studied. We have observed two time constants at the diamond/solution interface. Solution resistance was found to be constant irrespective of the electrode in the same electrolyte. DC polarization techniques such as linear and Tafel polarization have been used to evaluate the doped diamond/Mo and Mo for corrosion resistance characteristics interms of charge-transfer coefficients and corrosion rate. Cyclic voltammetry has been used to evaluate the doped diamond/Mo to study the background current response and the redox kinetics of ferri/ferrocyanide in 0.5M NaCl solution.