[en] We have studied the crystal structure, the magnetic and electron transport properties and the magnetoresistance effect of nitrogenation of La_2/3Ca_1/3MnO₃ by x-ray powder diffraction, magnetic measurement and standard four-probe resistance-temperature measurement. Nitrogenation results in an increase in the lattice parameter and unit cell volume, and induces the formation of a superlattice. The N atom prefers to occupy the 4c crystal position in the superlattice structure. Nitrogenation weakens the ferromagnetic ordering and results in the decrease of Curie temperature and the saturation magnetic moment but increases the electrical resistivity significantly. The electrical resistivity exhibits a metal-insulator (MI) transition, but the MI transition temperature decreases after nitrogenation. The behaviour of the electrical resistivity follows the equation ρ=ρ₀(1-aT+bT²+cT⁴) in the metal regime. However, it follows the formula ρ=ρ₀exp (E/k_BT) in the insulator regime. The magnetoresistance ratio measurement shows an increase of 15% after nitrogenation. (author)