Abstract: In this study, high-temperature superconducting samples of HgBa2Ca2Cu3O8+δ (Hg-1223) were synthesized using the Sol-Gel method and sintered at three different temperatures: 800°C, 825°C, and 850°C. Structural characterization using X-ray diffraction (XRD) confirmed the formation of the desired Hg-1223 phase, with varying degrees of phase purity depending on the sintering temperature. Lattice parameters, phase ratios, and crystallite sizes were calculated and correlated with the processing conditions. Surface morphology examined by scanning electron microscopy (SEM) at 5 μm magnification revealed clear grain growth and increased densification with rising sintering temperatures. The microstructural evolution contributed significantly to the electrical behavior of the samples. Electrical resistivity measurements as a function of temperature showed superconducting transitions in all samples with a constant onset critical temperature (Tc(onset) ≈ 171.3 K). The sample sintered at 850°C exhibited the sharpest transition (ΔTc ≈ 37.3 K), indicating improved homogeneity and stronger intergranular connectivity. All samples displayed comparable energy gap values (~0.026 eV), confirming the superconducting nature of the Hg-1223 phase. Overall, the results demonstrate that the Sol-Gel method is an effective route for producing high-quality Hg-based superconductors. The sample processed at 850°C achieved the best combination of structural integrity, phase purity, and superconducting performance, making it a promising candidate for future applications in high-temperature superconducting technologies