The results are given of detailed experimental studies of the model flue gas mixture irradiation by pulsed electron beams and electron-beam-initiated non-self-sustained discharges. The effects of the electron beam parameters, the external electric field and the composition of irradiated gas on the process of sulphur dioxide SO₂ removal are analysed. We demonstrate the existence of optimum values of the electron beam current density and pulse duration, and of the external electric field strength, at which the energy required to remove one SO₂ molecule is minimum. The energy cost and removal rate are given as functions of the concentration of SO₂, oxygen and water vapour in the mixture. The concentration limit that divides the chain and radical mechanisms of SO₂ removal is determined.