Ruthenium (symbol Ru, atomic number 44) is one of the six Platinum Group Metals (PGMs), alongside rhodium, palladium, osmium, iridium, and platinum. Grouped near the center of the periodic table, PGMs are among the most precious and rarest metals on earth, known for exceptional properties such as unrivalled catalytic activity, high melting points, durability, and biocompatibility.Â
With highly concentrated production, constrained supply and essential applications across industry and clean-energy technologies, PGMs are among the most strategically significant critical raw materials.Â
Silvery-white, hard, brittle and lustrous, ruthenium is the most ‘noble’ of the PGMs, alongside osmium. The term noble metal was first used in medieval alchemy, to describe a superior group of metals that do not rust, corrode or tarnish, even after exposure to acids or the harshest external environments.Â
Ruthenium was discovered in 1844 by the Russian chemist Karl Karlovich Klaus, who isolated the element from platinum ores found in the Ural Mountains. He named it after Ruthenia, the Latin name for Russia.
Among the PGMs, ruthenium stands out for its extreme hardness, strong electrical and thermal stability, and an unusual flexibility, allowing it to adapt to different chemical environments and switch roles within reactions. Only around 25 tonnes of ruthenium are mined each year, making it one of the scarcest of CRMs. Yet even tiny amounts of this super-metal make a big difference, with uses including hard disk drive coatings, electrical contacts and resistors, jewelry, anti-cancer drugs, catalysts and hydrogen electrolysis.
Ruthenium at a glance
Extremely rare
Ruthenium is extremely rare, occurring at about one part per billion (ppb) in the Earth's crust. This makes it one of the rarest of all non-radioactive elements. Ruthenium is not found on its own, but mixed together with other PGMs, often only at a trace level.
More oxidation states than almost any metal
Ruthenium can exist in more oxidation states than almost any metal. This ‘chemical flexibility’ allows it to interact with many different molecules and electrons, making it exceptionally useful in catalysis, electronics, and advanced chemical processes.
Extreme hardness with exceptional chemical stability
The metal combines extreme hardness with exceptional chemical stability. Unlike many metals, ruthenium remains stable under high heat (melting point above 2,300 °C), pressure, and chemically aggressive conditions. This makes it well suited for high‑wear electrical contacts, catalysts and coating applications, where failure is not an option.
Increasing resistance to corrosion
Adding even tiny amounts of ruthenium to alloys significantly increases their resistance to corrosion, especially in tough acidic or marine environments. This makes it valuable for chemical processing, energy infrastructure, and marine applications, where materials must survive extreme conditions.
2005 Nobel Prize in Chemistry
Ruthenium was central to the 2005 Nobel Prize in Chemistry. The breakthrough use of ruthenium-based catalysts, named ‘Grubbs catalysts’ after one of the winning scientists, enables complex chemical reactions in stable conditions, with low waste. This has transformed how medicines, plastics, and advanced materials are made worldwide.
