The deposition of cesium on type-304 stainless steel has been measured in vacuo using 137Cs-tagged cesium. Measurements were made at 650 to 1350°F over a cesium pressure range of 2 × 10−9 to 5 × 10−6 atm using specimens that had been vacuum baked at temperatures ranging from 650 to 1870°F for 18 to 90 h. Adsorption isotherms were characterized by an empirical isotherm that shows a linear variation of log pressure with surface coverage; the heat of sorption decreases linearly with coverage. Cesium plateout levels range from 0.55 mg Cs/m2 (based on the geometric surface of the specimen) on very clean surfaces to 80 mg Cs/m2 on surfaces that were slightly oxidized. The amount of cesium deposited is shown to be directly related to the temperature and duration of the bakeout period. Isosteric heats of adsorption vary from about 22 to 98 kcal/mol over the range of coverage.