A phenothiazine-derived diamine monomer, namely 3,7-bis-[4-aminophenyl(4'- methoxyphenyl)amino]-10-(4-methoxyphenyl)phenothiazine, was synthesized and led to new electroactive aromatic polyamides and polyimides. The resulting polymers were readily soluble in polar organic solvents and could afford strong and flexible film by solution casting. These polymers displayed a pink color change at their first-stage oxidation and blue color change at their second-stage oxidation. Cyclic voltammetry results indicated that the polymers showed two reversible oxidation redox couples at 0.47－0.61 V and 0.73－0.85 V. These polymers exhibited excellent electrochemical and electrochromic stability with good coloration efficiency.