The present study is focused on the capillary bridge (CB) behaviour in the vicinity of its critical state. As known, a critical state is an extreme, unstable point, by crossing which a given system passes from one state to another. In our case, this passage is from equilibrium (static) to a hydrodynamic state. The hydrodynamic process, called here hydrodynamic regime occurring in concave CB is characterized by local deformations in the region of its neck, registered via a high speed camera (∼1000 fps). The information obtained from the experiment is interpreted on the basis of a lubrication model. The theoretical evaluations correlate satisfactorily with the experimental data.