For mass spectrometry studies at low pressure, methenium can be obtained by ultraviolet photoionization of methyl radical, or by collisions of monatomic cations such as  and  with neutral methane. In such conditions, it will react with acetonitrile  to form the ion .
Upon capture of a low-energy electron (less than ), it will spontaneously dissociate.
It is seldom encountered as an intermediate in the condensed phase. It is proposed as a reactive intermediate that forms upon protonation or hydride abstraction of methane with FSOH-SbF. The methenium ion is very reactive, even towards alkanes.