Tetrahalomethanes are fully halogenated methane derivatives of general formula CFkCllBrmInAtp, where:
Each halogen ( F, Cl, Br, I, At) forms a corresponding halomethane, but their stability decreases in order CF4 > CCl4 > CBr4 > CI4 from exceptionally stable gaseous tetrafluoromethane with bond energy 515 kJ·mol−1 to solid tetraiodomethane, depending on bond energy.
Many mixed halomethanes are also known, such as CBrClF2.
Fluorine, chlorine, and sometimes bromine-substituted halomethanes were used as refrigerants, commonly known as CFCs (chlorofluorocarbons).