The new hybrid material tetrapropylammonium hydrogen selenate bis (selenic acid), N(C3H7)4[HSeO4][H2SeO4]2 (hereafter abbreviated TPSe) has been synthesized by slow evaporation technique at room temperature. Crystal structure, DTA-TGA measurements, Raman, Infrared spectroscopy, nuclear magnetic resonance (NMR) electrical properties, and optical properties were provided to characterize the TPSe. This crystal structure contains one organic cation [N(C3H7)4]+, one [HSeO4]− tetrahedra, and two neutral selenic acids H2SeO4. The inorganic [HSeO4]− and H2SeO4 species consist of infinite two-dimensional inter-linkers via strong hydrogen bonds (O-H⋯O), giving birth to trimmers [(H2SeO4)2 HSeO4]nn−. The IR and Raman spectra of the compound recorded at room temperature were studied in regard to the literature data, and on the basis of theoretical group analysis. The theoretical calculations using the density functional theory DFT at the B3LYP/6-31G(d) level, are made to study the optimized molecular structure, the vibrational spectra, and the optical properties of TPSe compound. Good agreements were found between the theoretical results and the experimental Raman, IR spectra and the molecular structure. The polarizability α, the hyperpolarizability β, and the electric dipole μ calculated using DFT/B3LYP-31G(d) exhibit the non-zero hyperpolarizability β of the TPSe, indicating that this material could be used in certain NLO applications. The thermal DTA-TGA analyses did not show any phase transition in the 333–500 K temperature domain. The complex impedance spectroscopy is measured and discussed in the temperature (290–363 K) and frequency (1 kHz−13 MHz) domains to study the electrical propreties of the compound.< Réduire