<p>The rising global energy demand necessitates the advancement of sustainable energy solutions. The inherent intermittency of renewable energy sources could be effectively mitigated by integrating electrolyzers and fuel cells, ensuring a consistent and reliable supply of clean energy. Among the various types of electrolyzers and fuel cells, solid oxide systems have garnered considerable attention and have become a significant focus of research due to their distinctive attributes, including the use of non-noble, cost-effective metal catalysts, high stability, and superior efficiency. This study examined the influence of transition metals (vanadium, chromium, manganese, and cobalt) doping on calcium titanate (CaTiO₃) perovskite electrolytes to enhance proton conductivity in protonic-solid oxide electrolyzers (P-SOEs) and protonic-solid oxide fuel cells (P-SOFCs). Electrochemical analyses revealed that doping with transition metals increased the concentration of oxygen vacancies within the crystal structure, thereby improving ionic conductivity. X-Ray diffraction (XRD) analysis confirmed that all synthesized materials exhibited well-crystallized structures devoid of secondary phases. X-Ray photoelectron spectroscopy (XPS) further demonstrated an increase in oxygen vacancy concentrations in the doped samples. Electrochemical impedance spectroscopy (EIS) indicated that the doped samples achieved higher ionic conductivities compared to undoped CaTiO₃, with the chromium doped (CaTi_0.95Cr_0.05O_{3−<i>δ</i>}, CTCr) sample exhibiting the highest conductivity of 4.05 × 10^–4 S&#xa0;cm⁻¹ at 500&#xa0;°C under hydrogen. The study concluded that doping CaTiO₃ with transition metals enhanced conductivity through mechanisms involving structural distortion and charge compensation. These findings highlighted the potential of such materials in achieving efficient energy conversion in P-SOEs and P-SOFCs.</p> Graphical Abstract <p></p>