Rhenium is a silvery transition metal with a melting point of 3186 degrees Celsius. It the rarest metal in Earth's crust making up only 1 part per billion or less. It was also the last naturally occurring non radioactive element to be discovered. It has properties somewhat similar to those of the noble metals. It has oxidation states ranging from -1 to +7. It was isolated in 1925 by Walter and Ida Noddack, and Otto Berg. They had to use 660 kilograms of molybdenite to isolate one gram of Rhenium.

Rhenium is used alloys to make them more durable and heat resistant. One use of these alloys are in military aircraft. Rhenium is also a valuable catalyst.