Two ladder-type oligoaniline derivatives with hydrophilic oligoethylene glycol side chains were synthesized in high yields via an optimized synthetic strategy, enabling investigation of side-chain effects on mixed ionic-electronic conductivity. Shorter glycol chains yielded conductivities 1 order of magnitude higher under low-humidity (ca. 45% RH) conditions, while both exhibited conductivity increases of approximately 2 orders of magnitude under high-humidity (ca. 97% RH) conditions.