Oxidation of a novel water-soluble tellurophene [2,5-tellurophene-bisphenoxy(octaethylene glycol monomethyl ether)] by peroxide is electrochemically reversible. This tellurophene can also be oxidized by self-photosensitized singlet oxygen in an aqueous solution. The oxidized tellurophenes are studied by optical absorption spectroscopy, (1)H NMR, and electrochemistry.