2,6-Naphthalenedicarboxylic acid is an organic compound with the formula C10H6(CO2H)2. This colorless solid is one of several isomers of naphthalenedicarboxylic acid. It is a precursor to the high performance polyester polyethylene naphthalate (PEN, poly(ethylene-2,6-naphthalene dicarboxylate)). It is also used in the synthesis of some metal-organic frameworks.