The effect of pH and type of doping acid on monolayer behavior is investigated for poly(o-ethoxyaniline). Doping during monolayer formation is essential for high-quality Langmuir-Blodgett (LB) films to be obtained. Langmuir films were spread on a variety of subphases, containing trifluoroacetic, hydrochloric, sulfuric or perchloric acids at different concentrations. Doping of the polymer occurs at pH values lower than 3 when spreading of the solution is improved. Pressure-area isotherms display less hysteresis and higher collapse pressures when the polymer is pre-doped and spread on a pH = 1 subphase. Under these conditions monolayers could be transferred from the aqueous subphase onto hydrophilic substrates in the form of Z-type LB films.