Fe-Cu-K/SiO2 catalysts prepared by varying the amount of active components have been investigated to explain the effects of active components on the activity, selectivity, product carbon number distribution, and nature of coke formation during Fischer-Tropsch synthesis. The catalysts were prepared by co-precipitation technique using silica as support, followed by adding K promoters by wet impregnation technique. Active component composition, textural properties, metal dispersion and acidity of the catalysts were determined by ICP, BJH, pulse chemisorptions and NH3 -TPD methods. Further surface morphology, structural characteristics and structural changes occurred during the course of FT synthesis were studied by XRD, SEM and EDAX (quantity and X-ray mapping). Fischer-Tropsch synthesis has been investigated in a fixed bed micro-reactor with in situ reduction of catalysts, using H-2 as a reducing agent. The identification of different key components present in liquid products formed was done by GC-MS method. The spent catalyst was also characterized to understand the catalyst deactivation. The results have been discussed in relation to the loading of active components on catalysts and their influence on the textural and morphological properties, structural characteristics, as well as catalytic activity, selectivity towards product distribution and properties and nature of coke formation. (C) 2013 Elsevier B.V. All rights reserved.