A thermal lance or thermic lance or burning bar is a tool which burns iron in an oxygen environment to create very high temperatures for cutting. It consists of a long iron tube packed with iron rods, which are sometimes mixed with aluminum or magnesium rods which increase the heat output. One end of the tube is placed in a holder and oxygen is fed through the tube.

The far end of the tube is usually lit by an oxyacetylene torch. It can also be lit by an electric spark, in which case the tube is connected to one terminal of a battery and the other terminal is connected to a copper electrode. The end of the tube is then rubbed against the copper electrode to produce sparks, which ignite the lance.

An intense flame is produced at the lit end and can be used to rapidly cut through a variety of thick materials including steel and concrete. The tube is consumed, so every few minutes the operator shuts off the oxygen, discards the remaining stub of a lance tube, and starts using a new one.

A thermal lance does not contain thermite, contrary to popular misconception.

Using a thermal lance for safe-cracking is a popular misconception^{[dubious – discuss]}. A number of lances are needed to cut into even the most basic safe, and make much noise and smoke, making stealthy safe-cracking impossible. Also, they can char and set fire to the safe's contents, such as paper money, which burns easily.

Thermal lances burn at 7000 to 8000°F (3870 to 4420°C)^{[citation needed]}, melting even rocks.