* Beryllium is used as an alloying agent in the production of beryllium-copper, containing up to 2.5% beryllium. Beryllium-copper alloys are used in a wide variety of applications because of their combination of high electrical and thermal conductivity, high strength and hardness, nonmagnetic properties, along with good corrosion and fatigue resistance. These applications include the making of spot-welding electrodes, springs, non-sparking tools and electrical contacts.

* Beryllium metal is, due to its stiffness, light weight, and dimensional stability over a wide temperature range, used in the defense and aerospace industries as light-weight structural materials in high-speed aircraft, missiles, space vehicles and communication satellites.

* Thin sheets of beryllium foil are used with X-ray detection diagnostics to filter out visible light and allow only X-rays to be detected.

* Sheets of beryllium ranging from 3mm (0.125") thick down to 25µm (0.001") thick are used as the output window in x-ray tubes, allowing x-rays to leave the tube while keeping a vacuum on the inside of the tube.

* Beryllium is an effective p-type dopant in III-V compound semiconductors. It is widely used in materials such as GaAs, AlGaAs, InGaAs, and InAlAs grown by molecular beam epitaxy (MBE).

* In the field of X-ray lithography beryllium is used for the reproduction of microscopic integrated circuits.

* In the telecommunications industry, Beryllium is made into tools that are used to tune the highly magnetic klystrons used for high power microwave transmissions for safety.

* Because it has a low thermal neutron absorption cross section, the nuclear power industry uses this metal in nuclear reactors as a neutron reflector and moderator.

* Beryllium is used in nuclear weapons for similar reasons. For example, the critical mass of a plutonium sphere is significantly reduced if the plutonium is surrounded by a beryllium shell.

* Beryllium is sometimes used in neutron sources, in which the beryllium is mixed with an alpha emitter such as 210Po, 226Ra, 239Pu or 241Am.

* Beryllium is also used in the making of gyroscopes, various computer equipment, watch springs and instruments where light-weight, rigidity and dimensional stability are needed.

* Beryllium oxide is useful for many applications that require an excellent heat conductor, with high strength and hardness, with a very high melting point, and that acts as an electrical insulator.

* Beryllium compounds were once used in fluorescent lighting tubes, but this use was discontinued because of berylliosis in the workers manufacturing the tubes (see below).

* The James Webb Space Telescope[4] will have 18 hexagonal beryllium sections for its mirrors. Because JWST will face a temperature of −240 degrees Celsius (30 kelvins), the mirror is made of beryllium, a material capable of handling extreme cold better than glass. Beryllium contracts and deforms less than glass — and thus remains more uniform — in such temperatures. For the same reason, the optics of the Spitzer Space Telescope are entirely built of beryllium.

* Beryllium is also used in the Joint European Torus fusion research facility and will be used in ITER, to condition the plasma facing components.[5]