The Collaborative International Dictionary of English v.0.48:

Denationalization \De*na`tion*al*i*za"tion\, n. [Cf. F.
   d['e]nationalisation.]
   The act or process of denationalizing.
   [1913 Webster]

WordNet (r) 3.0 (2006):

denationalization
    n 1: changing something from state to private ownership or
         control [syn: denationalization, denationalisation,
         privatization, privatisation] [ant: communisation,
         communization, nationalisation, nationalization]