An improved version of fast response ESR spectrometer was used to study the spectrum of e$sup -$/sub aq/ in several chemical systems. The strong e$sup - $/sub aq/ signal at g = 2.00033 was found in the methanol and sulfite systems. Ethylene, formate, and tert-butyl alcohol systems gave larger signals, and bromide and ferrocyanide systems gave smaller signals than the sulfite systems. In systems of carbonate, phosphite, hypophosphite, phenol, and hydroquinone the e$sup -$/sub aq/ ESR signal appeared in emission. The proposed explanation for the presence of the emission signal is that in the reaction between e$sup -$/sub aq/ and the counter radical in these systems, the product molecule preference is for the triplet state. A discussion of this theory is given. (DDA)