Abstract: An electrochemical reactor is provided, including an electrical connector including an end part occupying a position referred to as engaged in a stack of electrochemical cells, including: an electrical contact portion; and a blocking portion, including: either a blocking through-orifice receiving by insertion an abutment element of an electrochemical cell, or a blocking element introduced by insertion into an abutting through-orifice of the electrochemical cell, the insertion, when the end part occupies the engaged position, leading to the formation of an abutment opposing the retraction of the end part out of the engaged position.