The structures of sulfided Co-Mo-K/C catalysts were studied by means of X-ray diffraction (XRD), laser Raman spectra (LRS), and X-ray absorption fine structure (XAFS). Activities for alcohol synthesis via CO hydrogenation were used to characterize the catalytic performance of these catalysts. On the activated carbon support, molybdenum is mainly present as MoS2 species which shrinks with the cobalt loading, while cobalt is mainly present in the form of "Co-Mo-S" phase at the low Co loading and partly in a Co9S8-like structure at higher Co loading. The catalysts exhibit outstanding performance for higher alcohol synthesis due to the addition of the promotion of cobalt. The activity for alcohol formation is optimized at L a Co/Mo atomic ratio of 0.5. Co species operate as a synergistic system, rather than independently from the MoS2 phase.