A new Co(salen)-catalyzed hydrofluorination method for alkenes is reported, utilizing Et₃N·3HF as the sole source of both hydrogen and fluorine. This process operates via a polar-radical-polar crossover mechanism, enabling the selective formation of C(sp³)–F bonds from simple alkenes. The method is versatile, effectively converting a wide range of alkenes, including both activated and unactivated ones, into hydrofluorinated products. It was also applied to ¹⁸F-hydrofluorination reactions, enabling the introduction of ¹⁸F into potential radiopharmaceuticals. Mechanistic investigations using rotating disk electrode voltammetry and DFT calculations revealed the involvement of both carbocation and Co⁶V–alkyl species as intermediates during the fluorination step. The contribution of each pathway depends on the structure of the starting alkene. The method is efficient, with high yields and broad substrate tolerance, and is compatible with various functional groups. The reaction is also suitable for ¹⁸F-labeled tracers for PET imaging. The study highlights the importance of redox-neutral catalytic systems and the potential of Co(salen) complexes in hydrofluorination reactions. The findings demonstrate the effectiveness of the method in both synthetic and pharmaceutical applications.A new Co(salen)-catalyzed hydrofluorination method for alkenes is reported, utilizing Et₃N·3HF as the sole source of both hydrogen and fluorine. This process operates via a polar-radical-polar crossover mechanism, enabling the selective formation of C(sp³)–F bonds from simple alkenes. The method is versatile, effectively converting a wide range of alkenes, including both activated and unactivated ones, into hydrofluorinated products. It was also applied to ¹⁸F-hydrofluorination reactions, enabling the introduction of ¹⁸F into potential radiopharmaceuticals. Mechanistic investigations using rotating disk electrode voltammetry and DFT calculations revealed the involvement of both carbocation and Co⁶V–alkyl species as intermediates during the fluorination step. The contribution of each pathway depends on the structure of the starting alkene. The method is efficient, with high yields and broad substrate tolerance, and is compatible with various functional groups. The reaction is also suitable for ¹⁸F-labeled tracers for PET imaging. The study highlights the importance of redox-neutral catalytic systems and the potential of Co(salen) complexes in hydrofluorination reactions. The findings demonstrate the effectiveness of the method in both synthetic and pharmaceutical applications.