In this paper we present experimental data on the three-phase hydrogenation of 2,4,6-trinitrotoluene (TNT) to triaminotoluene. The experiments are performed in a cocurrent upflow packed bed reactor. Methanol is used as an evaporating solvent. The influence of the main operating parameters, the reactor pressure, the feed temperature and the molar ratio of hydrogen to TNT in the feed, are investigated experimentally. A rapid deactivation of the catalyst was observed. The rate of deactivation was investigated by performing experiments at standardized conditions at regular time intervals and by continuous operation of the reactor. Several experiments were done to find out if the catalyst could be regenerated in situ. This regeneration proved successful: the catalyst activity was practically equal to the initial one.