Abstract: A device for mixing two fluids, of which at least one is a liquid, which has a tubular vessel open on both axial ends for receiving the fluids, at least two nozzles which are separated from one another in space for supplying the fluids and a guide device one end of which communicates with the nozzles. At a location approximately in the middle of the guide device, it discharges into the vessel, the vessel surrounding at this point an impact zone in which fluid streams emerging from the guide device impact each other. The guide device is joined securely to the vessel and, one of the walls of the guide device defining a closed passage is the wall of the vessel.