Abstract Immobilization of anti-SEB on SiO 2, Pt and Au thin films have been carried out by using a conventional covalent bonding technique. AFM investigation showed that after the immobilization, a monolayer of the antibody molecules was formed on the SiO 2 film. By reacting the immobilized anti-SEB with gold colloid conjugated anti-IgG, gold particles were observed on the antibody immobilized film surface by AFM. Pt films showed the highest coverage of anti-SEB after immobilization. Impedance change of a Pt electrode in PBS solution was also investigated before and after the immobilization of anti-SEB.