Potassium hydrogenacetylenedicarboxylate

Potassium hydrogenacetylenedicarboxylate is a potassium salt with chemical formula KC₄HO₄ or K⁺·HC₄O₄⁻, often abbreviated as KHadc. It is often called potassium hydrogen acetylenedicarboxylate or monopotassium acetylenedicarboxylate.

The salt can be obtained from acetylenedicarboxylic acid and is a common laboratory starting material for the synthesis of other derivatives of that acid. In the crystalline form, the hydrogenacetylenedicarboxylate anions HC₄O₄⁻s are joined into linear chains by uncommonly short hydrogen bonds.