Direct measurements of the radical reaction products following the electrochemical and photochemical oxidation and reduction of a metallophthalocyanine pi-ring are reported, Electrospray mass spectrometry was used to detect the presence of the anion zinc(II) (1,4,8,11,15,18,22,25-octafluoro, 2,3,9,10,16,17,23,24-octaperfluoroisopropylphthalocyanine chloride, [ZnperF(64)Pc(-2) (Cl)](-), and its pi ring anion radical species, [ZnperF(64)Pc(-3)(Cl)](2-). This paper describes the use of ESI-MS techniques to determine the products of an on-fine, photochemical radical oxidation, using CBr4 as a sacrificial photoinduced oxidizing agent, which oxidized the radical, [ZnperF64Pc(-3)(Cl)]2- species to [ZnperF(64)PC(-2)(Cl)](-), where the complete reaction was detected directly by the mass spectrometer. This study makes use of electrospray mass spectrometry to detect the presence of an anion radical as the key component in the ring-reduced species and to monitor the immediate products of the important class of photochemical reduction and oxidation reactions in which radicals of the Zn Pc are formed in situ.