The alumina supported ruthenium catalyst was prepared by co-impregnation method and characterised using B.E.T. surface, area measurement and Atomic Absorption Spectroscopy. The prepared catalyst was subjected to Fischer Tropsch Synthesis with simultaneous addition of 2% ethene, propene and acetylene in the feed stream to investigate the possible intermediate in the CO/H-2 reaction. From the experimental data it could be concluded that the formation of > CH2 group on the surface of the catalyst is the possible intermediate which initiate the chain propagation for the formation of higher hydrocarbons in the Fischer Tropsch Reaction.