Modification of surfaces is currently a very active field of research. Modification by using organic molecules as precursor is attractive due to the large variety of available compounds. Although the electrochemistry of diazonium salts has been studied for more than 50 years, it was not until the early 1990s, that the formation of a film resulting from the electrochemical reduction of such salts have been demonstrated. Since then, many fundamental studies have led to a better understanding of the various processes involved in the grafting reaction. In the presentation, a brief summary of some important findings on the subject made by our group will be made. Also the presentation will show the new approaches currently developed in our laboratory for the chemical and electrochemical modification of surfaces.