Abstract: The vapor pressures of zinc and its chloride from a FeO-CaO-SiOE-Al₂O₃ slag system were measured by Knudsen effusion method under the conditions with varying parameters such as temperature and slag composition. The results show that the vapor pressures of metallic Zn and ZnCl₂ increase with increasing temperature. For ZnCl₂, the logarithm of vapor pressure is a linear function of the reciprocal of temperature. The slag basicity exhibits the different effects on the vapor pressures of metallic Zn and ZnCl₂. The former increases with increasing slag basicity, while the latter decreases. A high FeO content in the slag tends to increase the vapor pressures of metallic Zn and ZnCl₂.