The influence of different nitric acid concentrations (35, 5-0, 70 wt %) on the physicochemical properties of multiwalled carbon nanotube was investigated: 15 wt % cobalt was impregnated on acid treated nanotubes. The corresponding catalysts were characterized by BET, XRD, Raman, SEM, TEM,: TPR, CO chemisorption techniques to further study the impact of acid functionaliZation on textual properties, metal dispersion, crystallite size, defect generation, and reducibility of 15Co/CNT catalysts. The performance of prepared catalysts was tested for 30% CO and 60% H-2 with balanced Ar in a fixed bed microteactot for Fischer Tropsch synthesis at 220 degrees C, 2 MPa, and GHSV of 3000 cm(3).g(-1)-.h(-1). Pretreatment of CNTs with 70 wt % nitric acid exhibited improved physicochemical properties of 15Co/CNT catalyst and hydrocarbon yield by 35% as compared to untreated CNT supported catalyst.