Search for the invisibly decaying Higgs particle at LEP and the LHC

The Higgs particle can have dominantly invisible decay in a large class of Majoron models as well as some SUSY models. The LEP signal and mass limit for a Higgs particle undergoing invisible decay are explored. They are found to be very similar to those for the standard model decay. The best signatures and discovery limit for an invisibly decaying Higgs particle at the LHC are also discussed.