Cobalt sulfide nanoparticles were synthesized through a successive ionic layer adsorption and reaction (SILAR) method at room temperature. Co(NO₃)₂·6H₂O and thiourea [(NH₂)₂CS] aqueous solutions were used as precursors. Obtained cobalt sulfide nanomaterials were heated at 100ºC temperature in a vacuum. By XRD analysis mixed phases of Co₃S₄, CoS_1.097 and CoS₂ were obtained with dominance of Co₃S₄ phase. The average size of cobalt sulphide nanoparticles in mixed phases obtained at 8 cycles of the reaction was estimated 9.8 nm. The optical band gap of the Co_xS_y nanomaterials was found 1.59 eV. By SEM analysis the obtained cobalt sulfide nanocrystals display a rice-like morphology.