Single crystals of benzotriazole pyridine -2 -carboxylic acid (BTPCA), are grown by slow evaporation techniques. Various nucleation parameters have been determined, including radius of the critical nucleus (r*), nucleation rate (J), and interfacial ( sigma) and volume free energy ( Delta G v ). Powder X-ray diffraction experiment is performed to confirm the formation of crystal structure. BTPCA is experimentally characterized by FTIR (Fourier -transform infrared spectroscopy) and Ultraviolet (UV) spectroscopy and theoretically by density functional theory (DFT). The powder second harmonic generation efficiency is evaluated using Kurtz -Perry method. In molecular structure, charge transfer interactions leading to nonlinear properties have been studied by HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) analysis and natural bond orbital analysis. B3LYP/6-311 ++G (d, p) basis sets were used to determine linear and non-linear properties. In addition, BTPCA exhibits a blue luminescence, as indicated by its fluorescence analysis. From the Wooster ' s empirical relationship, the mechanical properties of the sample were evaluated.