A device for mixing fluids, in particular a gas injection valve, nozzle valve, mixing nozzle or jet compressor, is proposed. To that end, a first fluid-carrying device (12) for carrying a first fluid and a second fluid-carrying device (13) for carrying a second fluid are provided; the fluids are mixed with one another in a mixing region (16) that is in communication with the fluid-carrying devices (12, 13). In addition, a means (20) for generating turbulence in the applicable fluid and a heater, with which the fluid can be heated before reaching the mixing region (16), disposed downstream of the means (20) for generating turbulence in terms of the flow direction of the applicable fluid are associated with at least one of the fluid-carrying devices (12, 13). The proposed device is used in particular for mixing hydrogen and saturated steam and to deliver this mixture to a fuel cell.