Hybrid organic-inorganic halide perovskites like \([\text {NH}_3{-}{(\text {CH}_2)}_4{-}\text {NH}_3]\text {CdCl}_4\)   are promising for optoelectronic applications, yet their temperature-dependent properties are not fully characterized. This work employs density functional theory (DFT) with the GGA-PBE functional and plane-wave pseudopotentials, as implemented in Abinit, to explore the structural, optical, and thermoelectric behavior of \([\text {NH}_3{-}{(\text {CH}_2)}_4{-}\text {NH}_3]\text {CdCl}_4\)  . Simulations used a \({35}\,\text {Ha}\) energy cutoff and 11 \(\times \) 8 \(\times \) 8 k-point mesh, with experimental crystal data as input. The structure features inorganic ( \({[\text {CdCl}_4]}^{2-}\)  ) layers, organic ( \({[\text {NH}_3{-}{(\text {CH}_2)}_4{-}\text {NH}_3]}^{2+}\)  ) cations, and N–H–Cl hydrogen bonds linking both sublattices. Thermal cycling induces notable bandgap narrowing and enhanced optical absorption, which in turn improve thermoelectric performance and carrier transport. These findings highlight \([\text {NH}_3{-}{(\text {CH}_2)}_4{-}\text {NH}_3]\text {CdCl}_4\)  ’s potential for temperature-tunable optoelectronic and thermoelectric applications.