Third-order optical limiting action of 2-amino-5-nitro pyridinium chloride (2A5NPCl) crystals was demonstrated for protection of photosensitive components from damages induced by widely used green CW lasers. Crystals grown by slow evaporation possess lattice parameters of a = 9.968 angstrom, b = 7.731 angstrom, c = 4.802 angstrom and beta = 95.864. 2A5NPCl crystals are highly transparent with wide optical window of 400-1100nm. 2A5NPCl crystals exhibit strong saturable absorption and self-defocusing refraction. Third-order NLO coefficients of 2A5NPCl crystal was estimated to be n(2) = -3.20x10(-8)cm(2)/W, beta = -1.20x10(-4)cm/W and chi((3)) = 5.18x10(-6)esu. 2A5NPCl crystal exhibits OL action with onset limiting threshold of 14 mW.