The primary electroreduction behavior of 6-amino-5-nitroso-1,3-dimethyluracil (ANDMU) on an active carbon fiber (ACF) electrode in acidic aqueous solution was studied by cyclic voltammetry and ultraviolet spectrophotometry for application in electrochemical synthesis and electrosorption separation in the caffeine industry. On the ACF electrode at potentials more negative than −0.3 V versus SCE, ANDMU could be electro-reduced to 5,6-diamino-1,3-dimethyluracil. The mechanism of electroreduction of ANDMU is possibly coupling of two electron-transfer steps with electrocatalytic hydrogenation. ANDMU could also be electro-oxidized on an ACF electrode at potentials more positive than 0.8 V versus SCE. The potential window of ANDMU on the ACF electrode is deduced to be −0.3 to 0.8 V versus SCE under these experimental conditions. The results are indicative of high feasibility of electrochemical hydrogenation of ANDMU on an ACF electrode in caffeine green synthesis.