<p>Single crystals of dipotassium tartrate hemihydrate (DPTH) [K₂C₄H₄O₆ ‧ 0.5H₂O] were grown by the slow evaporation solution technique at room temperature. According to previously reported single-crystal X-ray diffraction (SC-XRD) data, DPTH crystallizes in the monoclinic system with a non-centrosymmetric space group <i>I</i>2. The obtained crystalline DPTH was subjected to vibrational, nuclear magnetic resonance (NMR), ultraviolet–visible (UV–Vis), photoluminescence (PL), and dielectric analysis. Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectral analysis revealed that the molecular structure contains the dipotassium cation along with L-tartrate anions. The presence of a molecular environment with hydrogen and carbon in the molecule was represented by the proton and carbon NMR spectrum. The transparency of the entire visible region was shown by the UV–Vis spectra, and 327.94&#xa0;nm was determined to be the lowest cutoff wavelength. The electrical transport behavior of DPTH was investigated through frequency-dependent dielectric constant and dielectric loss studies, providing insight into the polarization mechanisms, charge displacement, and alternating-current (AC) conduction behavior within the crystal lattice. The observed low dielectric loss at higher frequencies suggests minimal energy dissipation, which is favorable for optoelectronic and nonlinear optical (NLO) device applications. The second-harmonic generation (SHG) efficiency of the DPTH crystal was about 0.66 of the standard potassium dihydrogen phosphite (KDP), indicating its potential for NLO applications. Crystal Explorer software was utilized to compute both the two-dimensional (2D) fingerprint plot and the Hirshfeld surface, offering valuable insights into the overall packing features of the produced DPTH crystal.</p> Graphical abstract <p></p>