A range of pyrrole monomers with carboxyl derivatives both at the N-, and beta-ring positions were synthesized and, subsequently, were polymerized electrochemically at carbon, gold, and platinum electrodes. The resulting polymers, which were characterized with both electrochemical and spectroscopic methods, were then used to investigate the importance of polymer oxidation potential, polymer functionality, and backbone conductivity on the redox interaction with the small redox protein, cytochrome c. By choosing monomer substituents with varying side-chain length and steric bulk, it was possible to probe the nature of the protein-polymer interaction and to show how the heterogeneous rate constants, k(s), as an estimate for electron exchange between the electrode functionalized poly(pyrroles) and the protein, varied as a consequence of the structure of the matrix. The method provides a novel route for the modification of a wide range of conducting surfaces for the study of biological interfacial reactions, particularly those involving biomolecular recognition.