A process and apparatus for the separation of gas bubbles from a liquid which is subjected to a flow, in which a flowing portion of the liquid is brought into contact with an arcuate wall at an opening and deflected into a relatively quiescent liquid along a surface, so as to produce a vortex at the contact surface between the two liquid portions in such a manner as to project the vortex into the flowing portion as well as into the relatively quiescent portion, and whereby its axis extends in parallel or almost parallel to the contact surface, so that gas bubbles will be conducted from the flowing liquid portion by the vortex into the relatively quiescent liquid portion, from which the gas bubbles will then separate out under the influence of buoyant force.