The pyruvate ion is a biochemically important molecule, but its vibrational spectra appear not to have been studied previously in any detail. In view of this, and our interest in the vibrational spectra of simple organic acids and their derivatives, it seemed desirable to carry out a detailed analysis of the vibrational spectra of this ion. Sodium pyruvate is only sparingly soluble in water at ambient temperatures and is insoluble in common organic solvents. The spectra were therefore recorded on crystals which were purchased from Aldrich Chemical Company, recrystallized from distilled water and washed with CCl4. The crystal structure of sodium pyruvate has been determined previously by x-ray diffraction1. The molecule crystallizes in the P21/a space group with four molecules per unit cell. The CO2−group is rotated 18° from the plane containing the other heavy atoms.