The solubility of zinc in solid iron was determined by a static equilibrium method using two different types of equipment. The first apparatus used a sealed and evacuated fused silica capsule, with the zinc and iron at opposite ends of the capsule. The second apparatus used two vertical mullite or alumina tubes. One tube was partly inside the other with the zinc located on top of the inner tube. In both techniques, the temperature of the zinc fixed the partial pressure of zinc in the system. The results indicate that above an iron temperature of about 1,200 deg. C and below a p(zn) of about 1 atm, there is a linear relationship between zinc vapor pressure and zinc content. Therefore, for these conditions, zinc closely approximates henry's law. The results also indicate that there is little difference between the activity coefficient of zinc in alpha and gamma iron.