In this work, it has been intended to modify the polyaniline by means of the electrooxidation of a mixture of aniline and sulphanilic acid in a H2SO4 medium, obtaining a new copolymer which is going to be the object of the study. Changing aniline concentrations, limit anode potential values, polarization times and the scanning rate it will be possible to estimate the copolymer growth optimum conditions. It is also estimated the limit aniline concentration values which corresponds to a molarity range, from which the obtained polymer is the polyaniline and not the studied copolymer. Finally, it is studied the behaviour of the copolymer film in a dissolution without aniline and its chemical stability in front of a H2SO4 dissolution, when it is subjected to a periodical triangular scanning rate.