The Collaborative International Dictionary of English v.0.48:

denationalisation \de*na"tion*al*i*sa"tion\ n.
   same as denationalization.

   Syn: privatization.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

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