The effect of solution treatment temperature on hydrogen embrittlement (HE) of an Al–Zn–Mg–Cu alloy was investigated. Slow strain rate tensile tests in humid air and dry nitrogen gas were used to calculate the index of susceptibility to HE. Fracture morphology of the specimens were observed by scanning electron microscope. The grain boundary segregation of Mg, Zn and Cu was investigated using Auger electron spectroscopy for the specimens solution-treated in the temperature range 400–480 °C after fracture by a tensile test inside a vacuum chamber. The results showed that there is a strong correlation among the concentration of Mg, Zn and Cu at grain boundary, the index of susceptibility to HE and the fraction of brittle signatures in the fracture surfaces of the specimens with different solution treatment temperatures. When the segregation of the solutes kept at the minimum (at 440 °C), the HE behavior of the specimen was greatly improved.