<p>Europium (Eu²⁺)-doped barium aluminate (BaAl₂O₄) nanophosphor was successfully prepared via the sol–gel route. X-ray diffraction analysis confirmed the hexagonal BaAl₂O₄ structure with an average crystallite size of 20&#xa0;nm. SEM analysis revealed irregularly shaped, closely packed grains with slightly rough surfaces, indicating partial agglomeration of nanoparticles. The UV–Visible absorption spectrum demonstrated a broad absorption peak in the UV region, attributed to O²⁻ → Eu²⁺, confirming the effective incorporation of Eu²⁺ ions into the BaAl₂O₄ host lattice. Upon 397&#xa0;nm excitation, the photoluminescence spectrum shows a broad, intense blue-green emission peak at 495&#xa0;nm. This strong emission peak around the visible region was attributed to parity-allowed transition 4f⁶ 5d¹ → 4f^{7 8}S_7/2, which is highly sensitive to the crystal-field environment of the host lattice. The broad emission profile suggests efficient energy transfer and strong interaction between Eu²⁺ ions and the BaAl₂O₄ matrix. The observed intense luminescence and structural stability demonstrated that Eu²⁺-doped BaAl₂O₄ nanophosphor is a prominent material for solid-state lighting and persistent luminescent applications.</p>