Abstract: A multistage vortex reactor for contacting a gas stream with a gas, a fluid or other stream, comprising a housing having end walls and a peripheral side wall defining an elongated generally cylindrical vortex chamber having an inlet end and an outlet end, a first inlet in the inlet end of the vortex chamber for introducing a first gas stream in a swirling motion into the vortex chamber, a second inlet for introducing a second gas stream adjacent the inlet end of the vortex chamber for flowing around at least a part of the vortex chamber for separating the first stream from said chamber walls, a supply duct divides a gas stream into at least a first gas stream and a second gas stream and introduces the first gas stream into the first inlet in the vortex chamber and the second gas stream into the second inlet, an injector for introducing a liquid into the first gas stream in the vortex chamber, and an outlet for continuously removing gas from the vortex chamber.