1,3-Dimethyluracil is a pyrimidine derivative. Stability of the C6-centered carbanions derived from 1,3-dimethyluracil has been investigated in the gas phase and in DMSO and water solutions. The excited state structural dynamics of 1,3-dimethyluracil (DMU) in water and acetonitrile has been studied by resonance Raman spectroscopy. Crystal structure of 1,3-dimethyluracil has been reported. Ultraviolet irradiation of aqueous 1,3-dimethyluracil results in hydration of the 5:6 double bond of the uracil ring to form 1,3-dimethyl-6-oxy-hydrouracil.