A new interface between the cladding and the stack of pellets in a nuclear control rod. According to the invention, an interface joint made of a material transparent to neutrons, in the form of a structure with a high thermal conductivity and open pores, adapted to deform by compression across its thickness, is inserted between the cladding and the stack of pellets made of B4C neutron absorber material over at least the height of the stack. The invention also relates to associated production methods.