Abstract: Process for carrying out a sparged reaction, including providing one or a plurality of vertically-disposed reaction tubes, introducing a sparging gas under pressure into the bottom of the tube, separating and withdrawing the sparging gas from the top of the tube and passing the separated sparging gas in indirect heat exchange with at least part of the outside surface of the tube. The process is particularly suitable for carrying out an exothermic reaction, such as a fermentation reaction for the production of single cell protein, in which the bottom of a plurality of reaction tubes are disposed in a water bath, the withdrawn sparging gas is sprayed across the tops of the tubes, preferably after reducing the pressure to cool the same, and water is withdrawn from the bath and passed downwardly along the outside of the tubes.