The chemical synthesis of a new soluble polyaniline derivative, poly(o-phenetidine), was carried out with monomer excess and the polymer obtained was characterized by elemental analysis, FTIR, UV-vis spectroscopy, gel permeation chromatography, X-ray diffraction and cyclic voltammetry. The poly(o-phenetidine) has chemical and structural properties which are consistent with a pure polymer in the emeraldine oxidation state. Poly(o-phenetidine) Langmuir monolayers were spread from chloroform or dichloromethane solutions on an aqueous solution whose pH was varied from 6 to 2. Because kinetic effects on monolayer compression are extremely important for monolayers from preformed polymers, the influence of the various experimental parameters on the monolayer characteristics was investigated. It is shown that high transfer ratios are obtained in the LB deposition process when Langmuir monolayers are fabricated from very dilute dichloromethane solutions, spread on a low pH subphase, and compressed at a barrier speed of 30 mm min-1. The monolayer is then transferred onto a solid substrate by vertical dipping. UV-visible spectroscopy and cyclic voltammetry of the deposited LB films reveal essentially the same behavior as cast poly(o-phenetidine) films.