Low-energy electrons are involved in almost all of the physical, physico-chemical and chemical phenomena underlying radiation chemistry and play a central role in determining the effects of ionizing radiation chemistry. A detail quantitative description of their production is desirable, but not available in even the simplest liquids. The distribution defining the cascade of low-energy electrons produced in the radiolysis of liquid water is characterized. The most probable energy and mean energy for secondary electron produced by a primary ion are ∼9–10 and 50–60eV, respectively, depending on the specific energy of the primary ion. The energy spectrum of the sub-excitation electrons produced by attenuation of all electrons to <25eV is determined, and its mean is also 9eV.