This research represents the evaluation of electrochemical formation of conducting polymer polypyrrole-based composite layer, which could be applied in immunosensor design. Polypyrrole (Ppy) layer was formed by mean of potential pulses and bovine leukaemia virus (BLV) protein gp51 (gp51) was entrapped during this synthesis within formed Ppy layer (gp51/Ppy). Some Ppy layer formation aspects were evaluated and mathematical model, which is describing tendencies of gp51/Ppy layer formation, was adopted. The interaction of gp51/Ppy layer with specific antibodies that are present in the blood serum of BLV infected cattle was evaluated by pulsed amperometric detection. © 2014 Elsevier B.V.