A process for the recovery of oxides of sulfur from combustion waste gases, which comprises cooling said waste gases and forming entrained particles of sodium compounds, consisting essentially of sodium carbonate, by spray contact with sodium hydroxide or sodium carbonate, converting sodium carbonate in the particles to sodium sulfate by passing said oxides of sulphur containing waste gases and said sodium compound particles over plate-like packings, whereby said particles are comminuted to a finer particle size form so as to enhance the reaction of said sulfate particles with the oxides of sulfur in said waste gases, collecting entrained particles of said sodium compounds in a dust collector.