(S)-1,2-Propanediol is the chiral (S)-enantiomer of 1,2-propanediol, a colorless, viscous liquid with a molecular formula of C_H_O_. It is a low-molecular-weight diol featuring two hydroxyl groups, which confer high hygroscopicity and excellent solvent properties. Its primary applications are as a solvent, humectant, and moisturizing agent in the pharmaceutical and cosmetic industries. In pharmaceuticals, it is widely used as a co-solvent in oral, topical, and injectable formulations to enhance drug solubility and stability. In cosmetics and personal care products, it functions as a humectant and skin-conditioning agent, helping to retain moisture and improve product texture. Additionally, (S)-1,2-propanediol is generally recognized as safe (GRAS) for use in food and pharmaceutical applications. It is also employed as an antifreeze agent and as a precursor in the synthesis of specialty chemicals, though its primary commercial value lies in its role as a functional excipient and cosmetic ingredient.