Phenylethylamine is an organic molecule, meaning it is covalently bonded, and the main structure of the molecule is constructed from carbon atoms. In fact, by mass, Phenylethylamine is 79.27% carbon, while it is only 9.17% hydrogen and 11.56% nitrogen. By number, the molecule is 40% carbon, 55% hydrogen and 5% nitrogen. The formula of phenylethylamine is C₈H₁₁N. The actual structure of the molecule is fairly simple. It consists of a benzene ring, or "phenyl group." One of the positions on this ring is, instead of a hydrogen as the other five are, filled by an "ethylamine chain," which is a two-carbon backbone (the "ethyl group"), connected to an "amine," or a nitrogen and two hydrogens. Its molar mass is 121.2 grams per mole, and its density is .9528 grams per cubic centimeter.

At room temperature, phenylethylamine is a highly combustible liquid, its melting point is not known, and its boiling point is around 194-198^oC. When it is induced to decompose, one of the products is ammonia gas. Dangerous reactions also occur when it is exposed to strong oxidizing agents or strong acids. Otherwise, it is a fairly stable chemical.