The described work was carried out on November 2013 by the Istituto Nazionale di Ricerca Metrologica (INRiM) of Turin (Italy), for the participation fo the IX International Comparison of Absolute Gravimeters ICAG-2013 in the Underground Laboratory for Geodynamics in Walferdange, Luxembourg, organized by the University of Luxembourg. The experimental results of the absolute measurement of the free-fall acceleration g in the three sites dedicated to the comparison are reported. The measurements were performed with the transportable absolute gravimeter IMGC-02 of the INRIM. At the same time, 25 other absolute gravimeters coming for different parts of the world enjoined to the comparison. In the proximity of the measurement sites, a super-conductor relative gravimeter was enabled, in order to monitor the variation of the gravitation field along the days. With the IMGC-02 instrument a relative accuracy of few parts in 109 is reachable, i.e. measurement of g with uncertainty of tens microgals (1 μGal = 1 × 10−8 m s−2).