The RadiCoat 4-(Chloromethyl)benzene functionalised surface coating is a multilayer film on glassy carbon consisting of 4-(Chloromethyl)benzene groups, electrochemically immobilized through reduction of 4-(Chloromethyl)benzenediazonium tetrafluoroborate. The multiple surface Chloromethylbenzene groups makes the surface hydrophobic. In addition, these electrophilic groups may serve reactive moieties for nucleophilic substitution reactions to chemically immobilize e.g. biological markers or chemical functional groups. As an example, RadiCoat 4-(Chloromethyl)benzene glassy carbon has been used for immobilization of pyridine units (New J. Chem. 2005, 29, 659–666). RadiCoat 4-(Chloromethyl)benzene surface films are 5-7 nm and highly uniform.