This book examines cobalamins, including hydroxocobalamin, ethylcobalamin and glutathionecobalamin, highlighting their structure, synthesis and applications. Essential to health, cobalamins play a key role in DNA synthesis and red blood cell formation. Detailed synthesis protocols guarantee efficient methods for their production. In medicine, they are used to treat deficiencies and as antidotes, while in research, they serve as valuable tools for studying various biological processes. Analytical techniques such as microanalysis and UV-visible spectroscopy ensure product quality. Future prospects in this field promise to enrich our understanding of diseases and improve treatments.