Voltammetry of immobilised microparticles with a square wave potential scan (SQW) is used to study the phases composition of brass. Several electrolytes are considered in order to obtain peaks representing all the brass phases as well as to achieve the best resolution between peaks. Cyclic voltammetry was also used to characterise the electrode processes and the results obtained were in agreement with those from SQW voltammetry. The position and shape of the peaks changed with the media and concentration used to perform the experiment. Thiocyanate medium offered the richest information.