A peptide bond is a type of chemical bond that joins amino acids via covalent bonding. It is also called an amide bond that joins the carboxyl group of one amino acid to the amino group of another amino acid. The joining releases a molecule of water thus it is called dehydration synthesis reaction.

The joining of amino acids produces one hydrogen and oxygen atom from the carboxyl group while the amide group loses one hydrogen atom. A peptide is a biomolecule that is formed by joining a series of amino acids in a chain. Based upon the number of the monomeric unit the peptides may be classified such as a dipeptide that has two amino acids, and a tripeptide is a peptide having three amino acids.

A peptide bond or eupeptide bond is a predominant type of bond that is characterized by a link formed between alpha-carbonyl groups of one amino acid to the N-2 of the other amino acid. Isopeptide bond is another type of peptide bond that joins the amide group at the other position than the alpha position of the carbonyl group. These bonds can be degraded by the hydrolysis reaction or the addition of water. Usually, living organisms consist of some enzymes that complete the process of hydrolysis.