Gold, long prized for its chemical stubbornness, has finally been coaxed into reacting under conditions far removed from everyday experience. In experiments designed to mimic the crushing pressures and searing heat of planetary interiors, researchers have created a previously unknown compound: gold hydride, according to findings reported by Daily Galaxy. The result challenges decades of assumptions about how one of the most inert elements behaves when pushed to its physical limits.
For years, gold has been a trusted bystander in high-pressure experiments. Its resistance to chemical change made it ideal as a structural support or heating medium in studies of extreme matter. But inside giant planets, stars, and fusion devices, pressures reach tens of gigapascals and temperatures climb above 2,000 kelvin, conditions where familiar chemical rules begin to fail. Under those extremes, elements once thought unreactive can form unexpected bonds.
That is exactly what researchers observed when gold was subjected to pressures above 40 gigapascals and temperatures exceeding 2,200 kelvin. Using a diamond anvil cell and intense X-ray pulses from the European XFEL, the team watched hydrogen atoms infiltrate a gold lattice, forming a stable solid compound identified as Au?Hx. The work was published in the journal Angewandte Chemie in late 2025.
Detecting hydrogen directly is notoriously difficult, so the scientists tracked subtle changes in gold’s crystal structure instead. As pressure increased toward 80 gigapascals, the compound incorporated more hydrogen, adopting a hexagonal arrangement never before associated with gold. At those conditions, hydrogen entered a superionic state, moving freely through the solid gold framework. When the sample cooled back to ambient conditions, the structure reverted, confirming the process was reversible.
“This represents the first confirmed binary solid compound of gold and hydrogen,” said lead author Mungo Frost of the SLAC National Accelerator Laboratory, which helped analyze the data. The finding forces a rethink for scientists who rely on gold as a chemically passive reference material. Past high-pressure experiments may need to be revisited to rule out unnoticed interactions.
Beyond laboratory practice, the implications extend to planetary science and fusion research. Models of giant planet cores often involve dense mixtures of metals and hydrogen, and gold hydride adds a new data point for how hydrogen behaves in metal-rich environments. Researchers are now exploring whether similar reactions occur in other noble metals and whether gold hydride exhibits unusual electrical or thermal properties under pressure.
As experiments continue to probe matter at extremes closer to those found inside planets and stars, gold’s unexpected chemistry suggests that even the most familiar elements may still hold surprises when the universe’s true conditions are brought into the lab.