Calcium chloride (CaCl₂) is a commonly used reagent in biochemistry. It plays important roles in many biological processes, including signal transduction, muscle contraction, and maintenance of cell membrane and cell wall stability. CaCl₂ is used in the preparation and transformation of competent Escherichia coli (E. coli) and the transfection of eukaryotic cells with either plasmid DNA or high molecular weight genomic DNA. The CaCl₂-mediated electroporation of E. coli with the plasmid DNA pBR322 has been studied. CaCl₂ is used in the stabilization and two-dimensional crystallization of the NADH-ubiquinone oxidoreductase (complex I) from E. coli. The crystallization of porcine pancreatic elastase in the presence of CaCl₂ along with sodium citrate reveals the binding of calcium in the metal-binding site of the protein. The effect of CaCl₂ on the total fluorescence in the polymerization of the tubulin-like filamenting temperature-sensitive mutant Z (FtsZ) division protein of E. coli has been studied by a multiwell fluorescent assay.

Calcium chloride dihydrate has been used:

• in the formulation of media
• in sperm collection and preparation
• in cell culture and protoplast preparation