四碘化碳、四碘甲烷（分子式：CI₄），是四卤甲烷的一种，室温下为亮红色晶体，是少见的深色甲烷衍生物之一。其分子中仅含碳2%。

四碘化碳分子为正四面体型，C-I键长为2.12±0.02Å，分子内I-I距离3.459±0.03Å，存在相互作用。四碘化碳对光和热不稳定，而且六碘乙烷尚未制得，原因可能与上述相互作用有关。

四碘化碳为单斜晶系，晶胞参数a = 22.39、b = 12.93、c = 25.85 (.10 nm)、β = 125.26°。

分子中四个C-I所产生的极性为正四面体结构所抵消，分子偶极矩为0。

Carbon tetraiodide is CI₄, a tetrahalomethane. Being bright red, it is a relatively rare example of a highly colored methane derivative. It is only 2% by weight carbon, although other methane derivatives are known with still less carbon.

The tetrahedral molecule features C-I distances of 2.12 ± 0.02 Å. The molecule is slightly crowded with short I---I contacts of 3.459 ± 0.03 Å, and possibly for this reason, it is thermally and photochemically unstable. Hexaiodoethane is unknown, probably for the same reason.