CERN-LHC (Large Hadron Collider) accelerator facility will provide heavy ions (Pb–Pb) collisions with a center-of-mass (CM) energy of about 5.5 TeV per nucleon pair. In the extreme conditions of temperature and energy density created in such collisions, a transition from hadronic matter towards a deconfined state of quarks and gluons is predicted by Quantum Chromodynamics (QCD) calculations on the lattice. The Time Of Flight (TOF) detector system of the ALICE (A Large Ion Collider Experiment) apparatus, is presently progressing in the assembling process at LHC at CERN. The TOF, in combination with the other central tracking detectors of ALICE provides an excellent Particle IDentification (PID) in the momentum range 0.2 – 2.5 GeV / c for K / π and up to 4 GeV/ c for K/p. The ALICE TOF is a barrel detector consisting of double-stack Multigap Resistive Plate Chamber (MRPC) strips, equipped with readout pads. The MRPC is characterized by an intrinsic time resolution below 50 ps and an efficiency over 99%. The assembling procedures, the tests of mechanics, cooling system and electronics of the 8 m long TOF “supermodules”, together with the performance tests before installation in the experimental area, will be presented.