  High-efficiency and high-purity particle identification are fundamental
requirements for the success of the Belle II experiment, whose main goal is to
explore the new-physics scenarios in the CP-violating decays of the B mesons.
To achieve the required particle identification performances, the
Time-of-propagation counter has been installed in the central barrel region.
This unique device consists in 16 bars of fused silica that act simultaneously
as radiator and as light guide for the Cerenkov light. Unlike in the DIRC
detectors, the PID information is mostly extracted measuring the time of
propagation of the Cherenkov light in the radiator rather than its purely
geometrical patterns. We will present here a general overview of the status of
the TOP counter, including the estimation of the time resolution, the
calibration strategies and performances, and the first result obtained in the
commissioning phase, both using cosmic rays and $e^+e^-$ collision events
collected during the {\it phase II} pilot run of the Belle II experiment. These
are the first measurements of the particle identification performances of a
time-of-propagation detector in a full HEP experimental setup.
