{{DISPLAYTITLE:C2H2}} C2H2 may mean: Molecular formulae The molecular formula C2H2 (molar mass: 26.04 g/mol, exact mass: 26.01565 u) may refer to: Acetylene (or ethyne) Methylidenecarbene Vinylidene group Transcription factors C2H2 zinc finger, short for Cys2His2 a class of transcription factors with the small protein structural motif stabilised with Zinc ions