<p>Fire significantly impacts the mechanical properties of high-strength steel, leading to a substantial reduction in these properties. In applications involving secondary use, the influence of hydrogen on steel must be carefully considered. In industrial environments with high hydrogen content – such as in hydrogen energy, the chemical industry, and oil refining – high-strength steel may be exposed to hydrogen or hydride vapors for extended periods. This exposure may promote the diffusion and buildup of hydrogen atoms in the steel, consequently leading to the occurrence of hydrogen embrittlement. This research investigates the influence and effects of the electrochemical hydrogen charging process on the mechanical characteristics of high-strength steel exposed to simulated fire conditions at precise temperatures of 300°C, 500°C, 700°C, and 800°C. The findings reveal that a longer hydrogen filling duration is associated with a steady decrease in the mechanical properties of the steel, with the most significant reduction noted in elongation after fracture, which falls by 11% to 22%. At 800°C, the relationship between mechanical properties and hydrogen charging time is linear, whereas at temperatures below 800°C, this relationship becomes nonlinear. Additionally, the fracture morphology transitions from ductile to brittle with increased hydrogen charging time, and varying degrees of hydrogen embrittlement susceptibility appear on the specimen’s surface. As hydrogen charging time increases, the specimens exhibit hydrogen-induced cracks and damage of varying severity on their surfaces.</p>