A new metal-organic NLO single crystal of 2-Aminopyridinium bis[hexaaqua(cobalt(II)) sulfate] monohydrate (2APCS) has been obtained by the reaction of aqueous solution of 2-Aminopyridine and cobalt(II) sulfate heptahydrate and by room temperature slow evaporation process. Single crystal X-ray diffraction study of the grown single crystal confirms the P1¯ space group of a triclinic structure. The crystalline molecules are stabilized by elaborate O–H⋯O and N–H⋯O classical three dimensional hydrogen bonding network. The functional groups in the 2APCS were established by the FT-IR and Laser Raman spectroscopy. The obtained crystals were also characterized for thermal stability, dielectric, optical and nonlinear optical properties. Z-Scan technique was employed to observe the third order nonlinear optical susceptibility and was observed to be high. The optical limiting behaviour of the grown crystal is recognized mainly to nonlinear refraction. © 2019