In a current-limiter electrical circuit breaker with contact opening by electrodynamic repulsion, comprising at least a couple of contacts inserted between a power supply terminal and a load terminal, the contact-holder arms of which form two branches substantially parallel and closely approached to each other, through which cur­rents of opposite sign flow, a control mechanism kinema­tically linked to one of the two contact-holder arms through a compound toggle lever formed by two sectors and a spring suitable to pass from one side to the other side, and vice-versa, of a dead-point position, a block­ing device for the locking of the control mechanism in its active position, and thermomagnetic devices suitable to act on a release device for the disengaging of said blocking device; the hinge connecting the two sectors of the compound toggle lever to each other is constituted by a limitedly sliding slot-pin coupling, and the second one of the two contact-holder arms is linked to said release device through a kinematic chain.