This paper presents an evaluated compilation of equilibrium relative humidities in air versus temperature for 28 binary saturated aqueous solutions. The relative humidities range from about 3 to 98 percent. Data from 21 separate investigations comprising 1106 individual measurements were used to fit regular polynomial equations with two through four coefficients using the method of least squares. Equations and tables are provided along with estimated uncertainties in the correlated results. The study focuses on binary saturated aqueous solutions, primarily of single salts, which are useful for humidity control due to their high non-volatility. These solutions provide a fixed relative humidity at any given temperature, and different salts can be used to achieve different relative humidities. The study aims to compile data on a sufficient variety of saturated salt solutions to cover the entire range of relative humidity at reasonably close intervals. The data were adjusted to be consistent with temperatures on IPTS-68 and the most recent equations for the vapor pressure of water. Experimental techniques were analyzed, and uncertainties in the original data were estimated. The data were then used to calculate "best" values of relative humidity in air as a function of temperature from pure phase to approximately 10^5 pascal (1 atm) in pressure for these saturated solutions. Various methods were used to determine the water vapor in equilibrium with saturated salt solutions, including direct measurement of vapor pressure, dew point measurement, isoplastic vapor pressure measurement, relative vapor pressure measurement, measurement with a calibrated humidity sensor, and gravimetric determination. Each method has associated errors that vary with the level of vapor pressure and temperature. The data were fitted to regular polynomials using the method of least squares, with each datum weighted inversely proportional to its estimated uncertainty. The order of the polynomial was determined by an F-test or analysis of the result of fits to various orders. An arbitrary decision was made not to use any order higher than 3. The standard deviation of the predicted value was computed for each datum and fitted to a quadratic equation. The estimated uncertainty for each value of relative humidity was three times this value. The results show that the calculated relative humidities and their uncertainties differ for each of the three weightings. However, for the saturated solutions chosen for presentation, all relative humidities calculated from the three differently weighted fits agree with each other to within the assigned uncertainty. The uncertainties presented do not include uncertainties in the vapor pressure equation or enhancement equations. The data presented in table 2 are given at 5°C intervals over the temperature range of the original data with extrapolations beyond these ranges never exceeding 2.5°C. All calculated values of relative humidity are given to 0.01 percent relative humidity. The uncertainties presented are considered to be the best estimate of accuracy. The data are compared with other compilations, and it is noted that the comparison is over a limited temperature range and for only 17 of the 28 salt solutions evaluated.This paper presents an evaluated compilation of equilibrium relative humidities in air versus temperature for 28 binary saturated aqueous solutions. The relative humidities range from about 3 to 98 percent. Data from 21 separate investigations comprising 1106 individual measurements were used to fit regular polynomial equations with two through four coefficients using the method of least squares. Equations and tables are provided along with estimated uncertainties in the correlated results. The study focuses on binary saturated aqueous solutions, primarily of single salts, which are useful for humidity control due to their high non-volatility. These solutions provide a fixed relative humidity at any given temperature, and different salts can be used to achieve different relative humidities. The study aims to compile data on a sufficient variety of saturated salt solutions to cover the entire range of relative humidity at reasonably close intervals. The data were adjusted to be consistent with temperatures on IPTS-68 and the most recent equations for the vapor pressure of water. Experimental techniques were analyzed, and uncertainties in the original data were estimated. The data were then used to calculate "best" values of relative humidity in air as a function of temperature from pure phase to approximately 10^5 pascal (1 atm) in pressure for these saturated solutions. Various methods were used to determine the water vapor in equilibrium with saturated salt solutions, including direct measurement of vapor pressure, dew point measurement, isoplastic vapor pressure measurement, relative vapor pressure measurement, measurement with a calibrated humidity sensor, and gravimetric determination. Each method has associated errors that vary with the level of vapor pressure and temperature. The data were fitted to regular polynomials using the method of least squares, with each datum weighted inversely proportional to its estimated uncertainty. The order of the polynomial was determined by an F-test or analysis of the result of fits to various orders. An arbitrary decision was made not to use any order higher than 3. The standard deviation of the predicted value was computed for each datum and fitted to a quadratic equation. The estimated uncertainty for each value of relative humidity was three times this value. The results show that the calculated relative humidities and their uncertainties differ for each of the three weightings. However, for the saturated solutions chosen for presentation, all relative humidities calculated from the three differently weighted fits agree with each other to within the assigned uncertainty. The uncertainties presented do not include uncertainties in the vapor pressure equation or enhancement equations. The data presented in table 2 are given at 5°C intervals over the temperature range of the original data with extrapolations beyond these ranges never exceeding 2.5°C. All calculated values of relative humidity are given to 0.01 percent relative humidity. The uncertainties presented are considered to be the best estimate of accuracy. The data are compared with other compilations, and it is noted that the comparison is over a limited temperature range and for only 17 of the 28 salt solutions evaluated.