Hemin derivative having thienylene groups, hemin thienyl ester (HTE), was synthesized and its electrochemical behavior was analyzed in poly(ethylene oxide) (PEG) oligomers. A cyclic voltammogram of the HTE dissolved in dimethylformamide (DMF) showed redox peaks (E(1/2) = - 0.10 V vs. Ag) based on the heme (iron protoporphyrin IX). The HTE also showed the same redox behavior in PEO(200) (molar mass of 200). Symmetrical redox waves were observed in the cyclic voltammogram of the HTE adsorbed on the indium tin oxide (ITO) coated glass electrode in PEO(200). Its peak separation was about 10 mV and the quantity of electricity was constant and both were independent of the scan rate. These results indicated that HTE molecules were fixed on the ITO electrode as a monolayer. The thienylene group was confirmed to be effective to fix the redox active molecules on the ITO electrode suitable for the electron transfer even in the PEO oligomers.