gamma-NiB4O7 was synthesized in a high-pressure/high-temperature experiment at 5 GPa and 900 degrees C. The, single-crystal structure analysis yielded the following, results: space group P6(5)22 (No. 179), a = 425.6(2), c = 3490.5(2) pm, V = 0.545(2). nm(3), Z = 6, and Flack parameter x = -0.010(5). Second harmonic generation Measurements confirmed the acentric crystal structure. Furthermore, gamma-NiB4O7 was characterized via vibrational as well as single-crystal electronic absorption spectroscopy, magnetic measurements, high-temperature diffraction, differential scanning calorimetry, and thermogravimetry. Density functional theory-based calculations were performed to facilitate band assignments to vibrational modes and to evaluate the elastic properties and phase stability of gamma-NiB4O7.