Copolymers of aniline and 2-ethylaniline can be easily formed by electrochemical or chemical oxidation in acidic medium, but the composition of the polymeric chain differs from the composition of the synthesis solution. Copolymers formed from precursor solutions containing less than 30% (in moles) of 2-ethylaniline show intermediate properties between those of the homopolymers, and these properties vary gradually with the amount of 2-ethylaniline units in the copolymeric chain. The properties of those copolymers have been studied by UV–Vis and resonance Raman spectroscopies, cyclic voltammetry, two-probe conductivity and solubility measurements. Results obtained by these techniques corroborate the formation of a block copolymeric material.