C5H4

The molecular formula C5H4 (molar mass: 64.09 g/mol, exact mass: 64.0313 u) may refer to:


 * 3-Ethynylcycloprop-1-ene
 * 1,4-Pentadiyne
 * Penta-1,2-dien-4-yne
 * Spiropentadiene, or bowtiediene