Protein microarray is a promising technology that should combine rapidity and easy use with high throughput and versatility. This article describes a method in which an electrocopolymerization process is employed to graft biological molecules on to a chip so that surface plasmon resonance imaging may be used to detect molecular interactions. Copolymerization of pyrrole-modified protein and pyrrole is an efficient grafting process which immobilizes molecules at defined positions on a gold surface. Surface plasmon resonance imaging is an optical technique that allows real-time simultaneous detection of molecular interactions on a large number of spots without labeling. This method was successfully used to analyze antibody-antigen interactions. This illustrates its high specificity and good sensitivity and demonstrates its suitability for biological studies.