Understanding the salting effects on the solubility and transformation kinetics of amino acid solvates in aqueous solutions is important for a rational design of the industrial isolation and purification conditions of amino acid. We report measurements of L-phenylalanine anhydrate and monohydrate solubility as a function of temperature in aqueous NaCl, KCl, Na2SO4, and (NH4)(2)SO4 solutions with concentrations of 4 g/100 g of H2O in this work. It is found that salts play an important role in determining solubility reduction and solvated behavior, which had not been elucidated. This comparison has provided important insight into the dependence of L-phenylalanine solvates on temperature. The dependence of the L-phenylalanine anhydrate/monohydrate transformation kinetics on temperature in the presence of NaCl, as a typical salt, is discussed. It is noted that NaCl can markedly increase the rate of the transformation of L-phenylalanine between anhydrate and monohydrate compared with pure water. A simple model for the transformation kinetics based on the salt effect between anhydrate and monohydrate is established, which can quantitatively provide the observed experimental dependence of the transformation rate on time. This work can provide important instruction for optimum process control during industrial production of L-phenylalanine.