The product of oxidized 6-OHDA and GSH reacted in vitro has been identified by a variety of chemical and physical methods to be 2,4,5-trihydroxy-6-S-(glutathionyl)phenethylamine. Its chemical properties show it easily undergoes a variety of oxidative condensations and polymerization. Its oxidized form, the p-quinone, can be identified in small quantities in rat brain and mouse brain 1-3 h after 6-OHDA injection. This is believed to be the first report of a chemically identified species resulting from the in vivo interaction of 6-OHDA with CNS tissue.