Nanostructured metal materials are the frontrunners of numerous electronic advancements. While realizing such potential, it is indispensable to address their oxidation and stability drawbacks, which are due to their high surface energies. Here, we report printable and air-stable molecular metal ink materials from metal-organic decomposition by using copper ions, including both copper formate and aqueous copper-amine complexes. By complexing copper formate with amines, the decomposition temperature of the printed molecular copper ink can be achieved at 100 °C, while maintaining its electric conductivity. The printed copper conductors exhibit a high electric conductivity of 35 MS m-1 (>50% of bulk copper's electric conductivity at room temperature) and an electromagnetic interference shielding effectiveness of 63 dB. The findings shown here of the molecular decomposition ink are promising for applications in printable electronics.