The Collaborative International Dictionary of English v.0.48:

demonetization \de*mon`e*ti*za"tion\, n.
   The act of demonetizing, or the condition of being
   demonetized; specificially, the declaration by a government
   that something (e.g. gold or silver) is no longer the legal
   tender of a country; as, the demonetization of gold.
   [1913 Webster + WordNet 1.5]

WordNet (r) 3.0 (2006):

demonetization
    n 1: ending something (e.g. gold or silver) as no longer the
         legal tender of a country [syn: demonetization,
         demonetisation] [ant: monetisation, monetization]