This study relates to electron paramagnetic resonance (EPR) of the poly(o-phenetidine)-poly(styrenesulfonic acid) [P(O-P)-PSSA] and poly(2-ethylaniline)-poly(styrenesulfonic acid) [P(2-E)-PSSA] complexes; the polyaniline [PANI], poly(o-phenetidine) [POP],