Acetylene is the simplest member of unsaturated hydrocarbons called alkynes or acetylenes. This flammable, colorless gas is lighter than air so does not accumulate at low levels, where it could cause a potential hazard. It is generally supplied as dissolved in acetone or DMF (Dimethylformamide) in specially designed cylinders to prevent decomposition.

Typical Applications of Acetylene include flame heating, flame gouging, welding, flame hardening, flame cleaning, flame straightening, thermal spraying, spot-heating, brazing, texturing, profile-cutting, branding wooden pallets, wood-aging, and carbon coating. Acetylene is the only fuel gas recommended for underground working conditions because it is lighter than air. It is also the only fuel gas, for instance, which can be used to weld steel.