This study explores the structural, electronic, mechanical, and thermodynamic properties of cubic perovskite oxides \(\hbox {PbXO}_{3}\) (X = Ge, Si) under various pressures using the WIEN2k package. The optimized lattice parameters show excellent agreement with available experimental and theoretical data. Both the tolerance factor and phonon dispersion confirm the structural stability of these compounds under applied pressure. The electronic properties reveal a semiconducting nature with indirect band gaps of 1.67 eV for \(\hbox {PbGeO}_{3}\) and 2.13 eV for \(\hbox {PbSiO}_{3}\) , maintaining their p-type character across the investigated pressure range. The computed elastic and mechanical parameters indicate that both compounds exhibit ductile behavior at ambient conditions, while \(\hbox {PbSiO}_{3}\) transitions to a brittle nature at higher pressures. Thermodynamic parameters were analyzed as functions of temperature and pressure, providing insights into their thermal stability and mechanical robustness. Overall, the obtained results demonstrate that cubic \(\hbox {PbXO}_{3}\) (X = Ge, Si) perovskites are thermodynamically stable and hold promise for future energy-related applications.
