Pyrimidone is the name given to either of two heterocyclic compounds with the formula C<sub>4</sub>H<sub>4</sub>N<sub>2</sub>O: 2-pyrimidone and 4-pyrimidone. The compounds can also be called 2-hydroxypyrimidine or 4-hydroxypyrimidine respectively, based on a substituted pyrimidine, or 1,3-diazine, ring.
Chemists at UC Santa Barbara have determined that pyrimidone can be used for reversible, stable, long term thermal energy storage with an energy density of 1.6 MJ/kg, approximately double that of a lithium ion battery.
Derivatives of pyrimidone are the basis of many other biological molecules, including: