A numerical model has been proposed for the formation of active species in water by the action of pulsed UV radiation generated in self-sustained spark discharge with an energy per pulse of 5.9 × 10−2 J, a pulse duration of 100 μs, and a pulse repetition frequency of 10 Hz. The primary products formed in water are \(HO_2^ \bullet\) radicals, O· atoms, and N2O molecules. The yield of nitric acid and low (experimentally undetectable) yields of ozone and hydrogen peroxide are described in terms of the model. The concentrations of the active species in water have been calculated. The results can be used in biophysical research.