A cavitator to be used in a gas generator. The cavitator is provided with a cavitator inlet and a cavitator outlet having one or several cavitator channels having a cavitator channel inlet and a cavitator channel outlet. The cavitator channel or channels are further provided with cavitation inducing means, e.g. flow guiding or restricting means, wave shaped channel walls, protrusions and widenings, surface irregularities such as cavitation generating indentations or a combination thereof, for inducing a differentiated pressure within a liquid flowing through the cavitators. The cavitator further having an outer cavitator stator and an inner cavitator rotor arranged to rotate by a liquid flow through the cavitator. The rotation of the inner cavitator rotor will induce a differentiated pressure within the liquid in the cavitator promoting cavitation in the liquid flowing through the cavitator channels. A gas generator including such a cavitator as described herein is also disclosed.