Structures of the N-linked glycans released from porcine kidney diamine oxidase (DAO) were characterized utilizing various analytical techniques, including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS), high-performance capillary electrophoresis (HPCE), and high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The oligosaccharide sequences present in DAO were conclusively determined using specific exoglycosidases in conjunction with MALDI/TOF-MS. The structures found in the glycoprotein are primarily linear, di-, or tribranched fucosylated complex type. MS analysis of the esterified N-glycan pool derived from DAO indicated the presence of several di- and trisialylated structures.