Two new thiophene derivatives bearing redox active p-nitrophenyl units were synthesized and electropolymerized to conducting polymers. It is found that not only the structure of monomer, but also the employed polymerization conditions have considerable effect on the electroactivity of the bonded redox groups of resulting polymer films. Depending on used conditions such as polymerization time, the polymerization of the same monomer could result in a polymer with well-defined redox transition of the nitrophenyl group or a polymer, in which the redox group is completely electrochemical inaccessible. Using designed experiments, we explained this phenomenon. These investigations provide further knowledge about the behaviors of redox group attached to electrode surface.