Abstract5‐(3‐Thienyl)‐10,15,20‐triethyl‐21H,23H‐porphine (H2(ttep)) was synthesized and characterized. Oxidative polymerization of H2(ttep) gave a novel oligomeric porphyrin linked at the 2,5‐positions of the thienyl group. Electric conductivity of 4 × 10−1 S/cm after I2 doping indicated that the oligomer had a π‐conjugated structure with a delocalization of π electrons over the thienylene backbone. PM3 calculations revealed a low HOCO‐LUCO gap, which was consistent with the relatively high electric conductivity. Regioregular (head‐to‐tail) structure was inferred from spectroscopic and calculational results. The pendant porphyrin groups formed a regular J‐type array along the thienylene backbone, which was indicated by a significant red shift of the Soret band maximum. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5403–5412, 2006