Kelmis (in French: La Calamine) is a municipality located in the Belgian province of Liège. On January 1, 2006, Kelmis had a total population of 10,396. The total area is 18.12 km² which gives a population density of 574 inhabitants per km².
The municipality consists of the following sub-municipalities: Kelmis proper, Hergenrath, and Neu-Moresnet.
The territory around the Vieille Montagnezinc mine in Kelmis was a neutral condominium of Netherlands and Prussia (later Belgium and Germany) from 1816 to 1919 as Neutral Moresnet, with the Mayor of Kelmis being nominated by two commissionners from the neighbouring countries. Although there were attempts by locals at making it evolve into a fully independent microstate, all of them were thwarted and it remained under double-sovereignty and neutrality until its eventual annexation by Belgium after World War I.