In this study, cobalt disulfide (CoS2) nanoparticles have been successfully synthesized through a simple and facile solvothermal method. The experiments were carried out based on the thermodynamic calculations using FactSage software. The black nano-sized CoS2 powder has been produced in an autoclave reactor. The reaction parameters, such as the ratio of primary salts, effect of solvents, temperature and surfactant were optimized to obtain fine and uniform nanoparticles. The band gap energy of the samples was measured with butler relations. The results proved the production of highly pure CoS2 nanoparticles with a semi-spherical morphology.