5,10,15,20-Tetrakis(2'- and 3'-thienyl)porphyrins [H2T(2'-Thio)P and H2T(3'-Thio)P] and their metal [Zn(II) and CU(Il)] complexes were examined by electrochemical redox and axial ligation properties. A large anodic shift (100-150 mV) in reduction potentials was observed for MT(2'-Thio)Ps relative to MTPPs or MT(3'-Thio)Ps. MT(2'-Thio)Ps exhibited unusual redox behaviour and follows the trend in oxidation; CuT(2'-Thio)P > H2T(2'-Thio)P greater than or equal to ZnT (2'-Thio)P in contrast to their corresponding MTPPs, H2TPP > CuTPP > ZnTPP. It is reflected in the enhanced equilibrium constants (> 60%) for the ligation of nitrogenous bases with ZnT(2'-Thio)P when compared to ZnTPP. This is interpreted in terms of increased electron deficient nature of the ZnT(2'-Thio)P in contrast to Zn(3'-Thio)P or ZnTPP.