1-Thio-β-D-galactopyranose, sodium salt, is a thiosugar derivative where the anomeric oxygen atom of β-D-galactose is replaced by a sulfur atom. This structural modification imparts unique chemical and biological properties compared to its parent sugar. It is commonly used as a substrate or inhibitor for various galactosidases and glycosyltransferases in biochemical research. Its primary application is in the field of glycobiology and pharmaceutical research. It serves as a key building block for the synthesis of thioglycosides, which are important tools for studying carbohydrate-protein interactions, enzyme mechanisms, and as potential therapeutic agents. Furthermore, thiosugars like this compound are investigated for their use in drug delivery systems and as functional excipients due to their altered metabolic stability and membrane permeability. This compound is also relevant in the development of diagnostic reagents and probes. Its sodium salt form enhances solubility in aqueous buffers, making it suitable for enzymatic assays and in vitro studies. Proper handling is required as thiosugar derivatives may require specific storage conditions to maintain stability.