Molecularly imprinted polymers (MIPs) are attracting considerable attention nowadays, due to their “relative easy” concept and to the possibility of their use in several applications varying from drug release, protein and DNA sensing, to quenchers in SERS experiments or molecules and ions extraction. Molecular imprinting principal is based on the creation of specific and selective cavities in a 3D-polymeric network, which are complementary in size and shape of a target species, and which provide interaction points and a coordination sphere around the template molecule. In this work, we have designed and realized a MIP based electrochemical biosensor for the selective detection of prostate specific antigen (PSA). Pyrrole was chosen as functional monomer to realize the polymeric matrix. Several reasons have motivated our choice, mainly the fact that polypyrrole (PPy) is biocompatible and the fact that it can be used in aqueous and at neutral pH media. Choosing the most appropriate supporting electrolyte is another key element which can affect the MIP morphology, and thus the corresponding electrochemical response. Here, we have tested several kinds of electrolytes: NaCl, KCl and LiClO4 at a concentration of 0,1 M in either aqueous or PBS media. Electrochemical results indicate that the MIPs realized in PBS have better responses (in terms of current intensity values) than those realized in aqueous media, and that LiClO4 counter ions permit to obtain the most reproductible and stable films. Atomic force microscopy was investigated to determine the morphological structures of the realized MIPs. Results indicate that the films realized in PBS and in presence of LiClO4 are more uniform than all the other ones, confirming thus the electrochemical results.