<p>The development of stable electrocatalysts remains a critical challenge for proton exchange membrane fuel cells. In the present work, antimony-doped tin oxide was employed as a corrosion-resistant catalyst support. Crucially, the incorporation of antimony into the tin oxide lattice acts as an n-type dopant that fundamentally overcomes the inherently low electrical conductivity of the pure metal oxide, providing a highly conductive matrix for efficient electron transfer. Furthermore, the calcination temperature was systematically optimized to further improve its surface area and electronic conductivity. The optimized electrocatalyst, platinum supported on antimony-doped tin oxide calcined at 400&#xa0;°C, exhibited an electrochemically active surface area of 47.9 m² g_Pt⁻¹, which was comparable to that of commercial platinum on carbon 58.6 m² g_Pt⁻¹. Durability tests showed that this optimized electrocatalyst retained 77% of its initial electrochemical surface area after 10,000 accelerated aging cycles, whereas platinum on carbon lost approximately 42%. When implemented as the cathode catalyst in a proton exchange membrane fuel cell with a low platinum loading of 0.1 mg_Pt cm⁻², the developed electrocatalyst delivered a maximum power density of 622 mW cm⁻² at 80&#xa0;°C and 2 bar, decreasing by only 10.2% over 10,000 cycles of accelerated degradation testing. These results demonstrated that optimizing the antimony-doped tin oxide support structure significantly enhanced the stability of platinum-based catalysts while maintaining competitive activity.</p> Graphical Abstract <p></p>