This chapter briefly discusses the application, chemical properties and physical properties of pyridine. It presents detailed information on the air analysis and analysis of aqueous and nonaqueous samples of pyridine. Pyridine is used as a solvent and an intermediate in organic synthesis. It is colorless liquid with characteristic disagreeable odor. Pyridine is miscible with water and most organic solvents, weak base, toxic, and flammable. During the analysis of aqueous and nonaqueous samples of pyridine, pH of a measured volume of aqueous sample is adjusted to greater than 11. An organic solvent extract is concentrated and separated on a gas chromatography (GC) column. It is determined by a mass spectrometer, a nitrogen–phosphorus detector (NPD) or a flame ionization detector (FID). During the air analysis of pyridine, air is drawn through a solid sorbent tube packed with coconut shell charcoal.