Simple cations formed by adding a hydron to a hydride of a halogen, chalcogen or pnictogen are named by adding the suffix "-onium" to the element's root:  is ammonium,  is oxonium, and H2F+ is fluoronium. Ammonium was adopted instead of nitronium, which commonly refers to .
If the cationic center of the hydride is not a halogen, chalcogen or pnictogen then the suffix "-ium" is added to the name of the neutral hydride after dropping any final e.  is methanium,  is dioxidanium (HO-OH is dioxidane), and  is diazanium ( is diazane).