Oxy-Fuel Welding (commonly called oxyacetylene welding or oxy welding or in the U.S. gas welding) and Oxy-Fuel cutting are processes that use fuel gases and oxygen to either weld or cut metals.

There are a few differences between the two. In Oxy-Fuel welding, a welding torch is used to weld metals. In Oxy-Fuel cutting, a cutting torch is used to heat up ferrous metal to kindling temperature (approximately 980°C). A stream of pure oxygen is directed onto the hot metal which chemically combines with the iron which then flows out of the cut, or kerf, as an iron-oxide slag.

Torches that do not mix pure oxygen with the fuel inside the torch, but burn it with atmospheric air, are not oxy-fuel torches and can be identified by their single tank. (Oxy-Fuel welding/cutting needs two tanks, fuel and oxygen.) Most metals cannot be melted with such single-tank torches, so they can only be used for soldering and brazing, not welding.