A comparative study of the mentioned transitional metals makes the subject of this paper and could be considered as a contribution in the field. Dopant type (Fe,Ni and Co) and its concentration were assessed in relation with pollutant degradation kinetic. The catalyst dose, pH and initial NB concentration influence on the degradation efficiency were also evaluated in order to set up the optimal working conditions which assure pollutant's advanced degradation. the results were compared with those obtained using un-doped sol-gel TiO2.