It is used as a cell culture supplement for mammalian cells a precursor in glutathione (GSH) biosynthesis and in pharmaceutical biomanufacturing of recombinant proteins and monoclonal antibodies.

Its primary purpose is to provide bioavailable cysteine for protein synthesis and antioxidant pathways with improved aqueous solubility over neutral cystine for cell media formulation.

L-Cystine dihydrochloride is a white to pale yellow crystalline powder the dihydrochloride salt of the L-enantiomer of cystinea disulfide-bridged dimer of L-cysteine featuring two amino thiol (oxidized) and carboxylic acid groups linked by a -S-S- bond with molecular weight 313.22 gmol and high water solubility.