In this paper we present experimental data on the three-phase hydrogenation of 2,4,6trinitrotoluene (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. 'Author to whom correspondence should be addressed. will model our system and compare the model calculations to the experimental data. It was observed that the catalyst deactivates quickly. Therefore, regeneration experiments were done in order to find out if the catalyst can be regenerated in situ.