This paper presents the effects of noble metal modification of Co-HPS (high porous saponite) on thiophene hydrodesulfurization. The modification was done by two different ways: (1) single noble metal and (11) bi-noble metal. The noble metal loading was varied from 0.1 to 2 wt.% of the catalyst. In catalyst preparation direct impregnation technique was used for the loading of noble metal and an ion-exchange was followed for Co loading on HPS. The catalysts were characterized by elemental analysis and temperature programmed reduction (TPR). Elemental analysis shows that the Co loading was slightly affected by noble metal modification. TPR study displayed that the reducibility of the catalysts was enhanced in presence of noble metal(s). Thiophene hydrodesulfurization activities were measured in a pulse micro reactor. The noble metal modified catalysts exhibited significantly higher activity as compared to the Co-HPS. Rh shows the highest activity among the three noble metals used for Co-HPS modification. The thiophene hydrodesulfurization activity was further enhanced by a bi-noble metal modification. The Pt-Rh combination shows better performance as compared to the Pd-Rh combination. (C) 2004 Elsevier B.V. All rights reserved.