A new nonlinear optical single crystal of Guanidinium Propionate (GP) has been grown from the aqueous solution by slow evaporation method. Orthorhombic structure with Pbca space group was confirmed by single crystal XRD. The crystal packing is identified to the stabilized through three dimensional hydrogen bonding network between cation and anion N-H center dot center dot center dot O hydrogen bonds leading to three ring motifs viz. R-1(2)(4), R1(6) and R-1(2)(6). The grown crystals were characterized by thermal, mechanical, dielectric and optical studies. The third order nonlinear optical properties such as nonlinear absorption coefficient, nonlinear refractive index and susceptibility were calculated by Z-scan technique. (C) 2018 Elsevier B.V. All rights reserved.