[en] Sample of ¹⁰⁰MoO₃ with molybdenum enriched in ¹⁰⁰Mo to 99.5% and mass of 1199 g was measured deep underground (3600 m w.e.) in the Laboratori Nazionali del Gran Sasso of INFN, Italy; during 17249 h with a low-background set-up with 4 HP Ge detectors. After 2β2ν decay of ¹⁰⁰Mo to the 0⁺₁ excited level of ¹⁰⁰Ru (E_exc = 1131 keV), two γ quanta of 540 keV and 591 keV should be emitted in deexcitation process. Both these γ's are observed in the accumulated data as in coincidence spectrum as well in 1-dimensional sum spectrum. Measured half life is T_1/2 (7.0^+1.1_-0.8) x 10²⁰ yr, in agreement with positive results obtained in previous experiments.