The Argon Dark Matter (ArDM) experiment is a search for direct evidence of Weakly Interacting Massive Particle (WIMP) as Dark Matter candidate, with a ton-scale double phase liquid argon Time Projection Chamber (TPC). The scattering of the WIMP induces the recoil of an argon nucleus, that excites and ionizes the surrounding argon atoms. The detector design allows to detect independently the ionization and the scintillation signals. The background rejection is based on the time distribution of

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... e scintillation photons and on the ratio of the ionization charge to the scintillation light. The detector is presently under construction and commissioning on surface at CERN. Cryogenic operation, light detection, high voltage system and a preliminary charge readout were recently tested. This article describes the experimental apparatus and presents some preliminary results from the most recent run.