CO atmosphere plasma and first H2 then CO plasma were attempted to substitute the traditional "calcination-reduction-carburization" processes for the preparation of metallic cobalt phase with hcp structure. CoRu/SiO₂ catalyst precursor was prepared via incipient wetness impregnation. Characterization and catalytic results showed that CO could be decomposed in glow discharge plasma field, a large fraction of carbon species was deposited as elementary substance on the catalyst surface, while some of the carbon reacted with cobalt and formed cobalt carbide, which could transform into Co0 with hcp structure after reduction. The hcp structured cobalt containing catalysts showed higher initial Fischer-Tropsch synthesis activity than both calcined and air plasma treated samples.