The preparation and electropolymerization of a new porphyrin monomer with an amino group connecting the porphyrin core and aniline unit were studied. Cyclic voltammetry, FTIR spectroscopy, and a tandem quadrupole/time of flight mass spectrometry with matrix-assisted laser desorption/ionization source (MALDI-QqTOF) were used for the characterization of poly(5-(4'-aminophenylamino)-10,20-diphenylporphyrin) (PAPADPP). The PAPADPP formed a smooth layer on the Indium tin oxide (ITO) electrode and grew perpendicular to the electrode surface. An oligonucleotide (ODN)-probe was physisorbed onto the PAPADPP film and tested for hybridization with complementary and noncomplementary ODN segments. Biological recognition was monitored by comparison of the electrochemical signals (cyclic voltammogram) from single and double strand state oligonucleotides. The morphology of the physisorbed ODN-probe and its hybridization were observed on ITO electrodes using AFM and SEM.