Tritium is the radioactive hydrogen isotope in IndustrialCraft 2 Experimental, bred from Lithium rather than mined or crafted on a workbench. To make Tritium, a player places a Lithium Fuel Rod next to a Uranium or MOX Fuel Rod inside a running Nuclear Reactor; the neutron flux irradiates the lithium and converts it into a Tritium Fuel Rod over the reactor cycle. The conversion mirrors real-world tritium breeding and gives IC2 a long production chain that ties fission power to fusion power. Tritium cannot be found naturally and is never an output of a crafting grid.

Tritium Fuel Rods exist to feed the IndustrialCraft 2 Fusion Reactor together with Deuterium, delivering far more energy than the uranium that bred them. A single Fusion Reactor run consumes Tritium and Deuterium cells to produce millions of EU, which is why late-game IC2 bases invest in a dedicated Lithium farm and a continuously running fission reactor just to supply Tritium. Players store Tritium in the reactor chamber or in cans next to the Fusion Reactor, and the rare isotope becomes the long-term bottleneck for any base that wants to move past uranium power.