Electrochem. and phys. properties of polycryst. B-doped diamond electrodes with a metallic conduction grown by MPCVD and HFCVD were studied with the goal to use them as cathodes, for the electrochem. redn. of nitrate in neutral solns. All electrodes contain a mean B concn. [B] >3 * 1020/cm3 and show a significant redn. of nitrate. However, the higher efficiency is obtained for the electrode having the highest [B] (1.5 * 1021/cm3) and the lowest concn. of parasitic phases. The anal. of the Raman spectrum proved to be a valuable tool to probe these characteristics. Quant. anal. of the solns. showed that the relative concns. of the nitrogenous species formed during the redn. of nitrates at -2 V do not depend on the B doping level. [on SciFinder (R)]