This article investigates the inconsistencies in Tafel slope analysis for hydrogen evolution reactions (HER). The Tafel slope is a critical kinetic parameter for understanding electrochemical reactions, including HER. However, linear fitting of polarization curves in N₂-saturated electrolytes is often plagued with inconsistencies. The study reveals that Tafel slopes derived from this method are loading- and potential-dependent, and can exceed theoretical limits. These discrepancies are attributed to locally trapped HER-generated H₂ in the catalyst layer, which affects the HER current and leads to artificially lower or higher Tafel slopes. The Butler-Volmer (B-V) method, which accounts for both HER and HOR currents, offers a more reliable approach for pure Pt catalysts but is less applicable to transition-metal decorated Pt surfaces. The study emphasizes the challenges in Tafel slope analysis and the need for strict controls for reliable comparisons among different catalyst systems. The Tafel slope is influenced by H₂ diffusion in the catalyst layer, with microdiffusion and interfacial-diffusion playing a dominant role in hindering HER current growth. The study also highlights the impact of H₂ reoxidation on Tafel slopes, showing that the linear fitting method can lead to artificially smaller Tafel slopes in certain conditions. The article concludes that strategies to mitigate mass transport limitations, such as using thin catalyst layers and superaerophobic surfaces, are desirable for improving the reliability of Tafel slope analyses. The study underscores the importance of careful experimental design and the need for alternative analysis methods when dealing with complex HER catalysts.This article investigates the inconsistencies in Tafel slope analysis for hydrogen evolution reactions (HER). The Tafel slope is a critical kinetic parameter for understanding electrochemical reactions, including HER. However, linear fitting of polarization curves in N₂-saturated electrolytes is often plagued with inconsistencies. The study reveals that Tafel slopes derived from this method are loading- and potential-dependent, and can exceed theoretical limits. These discrepancies are attributed to locally trapped HER-generated H₂ in the catalyst layer, which affects the HER current and leads to artificially lower or higher Tafel slopes. The Butler-Volmer (B-V) method, which accounts for both HER and HOR currents, offers a more reliable approach for pure Pt catalysts but is less applicable to transition-metal decorated Pt surfaces. The study emphasizes the challenges in Tafel slope analysis and the need for strict controls for reliable comparisons among different catalyst systems. The Tafel slope is influenced by H₂ diffusion in the catalyst layer, with microdiffusion and interfacial-diffusion playing a dominant role in hindering HER current growth. The study also highlights the impact of H₂ reoxidation on Tafel slopes, showing that the linear fitting method can lead to artificially smaller Tafel slopes in certain conditions. The article concludes that strategies to mitigate mass transport limitations, such as using thin catalyst layers and superaerophobic surfaces, are desirable for improving the reliability of Tafel slope analyses. The study underscores the importance of careful experimental design and the need for alternative analysis methods when dealing with complex HER catalysts.