Reactions of the 2-phosphaethynolate anion (PCO-, 1) with ammonium salts quantitatively yielded phosphinecarboxamide (PH2C(O)NH2, 2). The molecular structure and chemical properties of 2 were studied by single-crystal X-ray diffraction and multielement NMR spectroscopy. This phosphorus-containing analogue of urea is a rare example of an air-stable primary phosphine.