The effect of addition of the chelating agent nitrilotriacetic acid (NTA) to the impregnation solution of ammonium heptamolybdate (AHM) for preparation of Mo/Nb₂O₅ hydrodesulfurization (HDS) catalysts was studied. The Nb₂O₅ support was obtained by calcination of commercial Nb₂O₅.xH₂O at 400 ºC and its surface area was 93 m² g^-1. In contrast to previous papers on Co(Ni)Mo/Al₂O₃ hydrodesulfurization catalysts modified with NTA, NH₄OH was not used in the preparation of AHM-NTA impregnation solution in the present work; the natural pH of this solution was about 2. The catalysts were tested in HDS of thiophene. The Mo/Nb₂O₅ samples prepared with the use of NTA (NTA-Mo/Nb₂O₅) were not calcined before sulfidation. The dependence of weight activity on MoO₃ loading was compared for Mo/Nb₂O₅, NTA-Mo/Nb₂O₅ and conventional Mo/Al₂O₃ catalysts. The activity of Mo/Nb₂O₅ samples was low, irrespective of loading. The activity of Mo/Al₂O₃ catalysts increased with loading up to the monolayer loading of about 22 wt.% MoO₃ (S_BET of Al₂O₃ was 262 m² g^-1) and was much higher than that of Mo/Nb₂O₅ samples. Surface area of sulfided NTA-Mo/Nb₂O₅ catalysts was low, only about 40 m² g^-1. However, their activity increased with loading up to the loading of 25 wt.% MoO₃, which was far above the monolayer loading. Moreover, at the same loading, activity of NTA-Mo/Nb₂O₅ catalysts was higher than that of corresponding Mo/Al₂O₃ catalysts. At the loading of 22 wt.% MoO₃, the relative activity of NTA-Mo/Nb₂O₅ catalyst vs. Mo/Al₂O₃ catalyst was 1.2 when normalized to weight and 5.1 when normalized to surface area.