Heavy Ion Physics with the ALICE detector at the CERN LHC In 2007, the Large Hadron Collider at CERN is scheduled to start operation with proton collisions at 14 TeV and later, in 2008, with heavy ion beams at 5.5 TeV/nucleon. At some 30 times the energy of RHIC, the LHC will open a new chapter in the study of nuclear matter under extreme conditions. After a brief reminder of the motivation and goals of heavy ion physics, the talk will give an overview of the heavy ion program at the LHC, in particular pointing out topics which are complementary to the current RHIC program, and describe in some detail the aims and status of the dedicated heavy ion experiment ALICE . ALICE (A Large Ion Collider Experiment) is large state-of-the art detector, dedicated and optimized to study heavy ion reactions at LHC. It measures 16 x 26 meters, weights about 10,000 tons and utilizes a number of novel detector technologies (TOF, RICH, high granularity silicon detectors and TPC) specifically developed for the highest multiplicities anticipated at LHC (several ten thousand particles per event in the acceptance). The ALICE Collaboration consists of about 1000 members from over 80 Institutes in some 30 countries.