<p>The structural, optoelectronic, elastic, thermodynamic, and mechanical properties of Sr₂XH₇ (X = B, Ga, and Al) complex hydrides are investigated in this study using HSE06 functional computations in density functional theory (DFT). The measured direct band gaps for Sr₂BH₇ (1.044 eV), Sr₂GaH₇ (2.295 eV) and the indirect band gap for Sr₂AlH₇ (3.273 eV) hydrides show that they are semiconductors and suitable for hydrogen storage applications. Hydrogen atoms have strong localized regions with values closer to 1.0, indicating their anionic character (H^-) due to charge transfer from strontium. From measured results, all hydrides possess high absorption coefficient (10⁵cm^–1), dielectric function (7–9), refractive index (2.5-3.3) and peaks appear in the visible and near-UV regions. The mechanical characteristics of all hydrides exhibit anisotropic behavior in the XY, YZ and XZ directions, and their mechanical parameter (B/G &gt; 1.75) confirms their ductile nature and potential for optoelectronic applications. The thermodynamic properties are investigated using the Density Functional Perturbation Theory (DFPT) technique. The zero point energies for Sr₂XH₇ (X = B, Ga and Al) hydrides are 6.1101 eV, 5.0702 eV and 5.2436 eV, respectively. Variations in these zero-point energies reveal strong bond strengths and atomic interactions. The alkaline earth metal poly-hydride family members Sr₂XH₇ (X = B, Ga and Al) have shown good GHSC values for Sr₂BH₇ (3.66%), Sr₂GaH₇ (2.80%) and Sr₂AlH₇ (3.37%), indicating their potential for next-generation hydrogen storage applications.</p> Graphical Abstract <p></p>