Investigation of the kinetics of disappearance of optical absorption arising during pulse radiolysis of 14.5 M aqueous KOH solutions revealed that the laws of disappearance of absorption at λ=650 nm and λ=720 nm are different. It is suggested from the spectroscopic data obtained earlier(1)that in the region 720 nm, in addition to the hydrated electron, another short-lived particle absorbs light. The modeling of chemical processes occurring in the system by means of an analogue computer allowed to determine the extinction coefficient of this particle, which is equal to 1.0×l04I/mol cm, and also the rate constants of the reactions of its formation and disappearance.