Six polyphenazine electrodes modified with platinum and silver nanoparticles deposited over conducting polymers have been prepared using electrochemical techniques. Phenazine monomers were electropolymerized on Indium tin oxide (ITO) and their morphology was explored by SEM-EDX and Raman spectroscopy. The main findings indicated that the polymers are not homogenously electro-deposited, having pores where metal nanoparticles can be nested, which can play an important role in the ionic exchange with the electrolyte. At longer deposition times, formation of clusters is observed with a loss of electrocatalytic activity and at shorter deposition times the growth step is not yet started and catalysis does not occur. Platinum nanoparticles with sizes of 10-60 nm are formed on the polymer agglomerates. Electrochemical measurements of H2O2 and H2O2-ascorbic acid were carried out as a model system and the electrodes have been characterized by SEM-EDX. The size of the nanoparticles and their aggregates decreased with respect to those of the original size. After an electrochemical cleaning, the sizes of aggregates were recovered which justify the reproducibility of the sensor. For Ag/Polymer/ITO, in all of cases, formation of dendrites plus silver nanoparticles was observed by SEM-EDX. (C) 2018 Elsevier Ltd. All rights reserved.