Benzyl-PEG5-amine is a PEG linker containing a benzyl protecting group and a free terminal amine. Benzyl groups are used to protect alcohol moieties and can be removed via hydrogenolysis. The primary amine can react with carboxylic acids, activated NHS esters and other carbonyl compounds. The hydrophilic PEG linkers increase the water solubility of a compound in aqueous media.