Abstract: Pure conducting hydrogel precursors and hydrogels formed of pure conducting polymer materials having a combination of high electrical conductivity, high stretchability, low Young's modulus, superior mechanical, electrical and electrochemical stability, and tunable swelling behaviors in wet physiological environments. The hydrogel precursors and hydrogels are fabricated by adding a polar organic solvent to an aqueous solution of the pure conducting polymer material, followed by controlled dry-annealing to form a hydrogel precursor which can be subsequently rehydrated to form a pure conducting polymer hydrogel which comprises at least 99% of the pure conducting polymer.