The composite diamond/titanium electrode which has been investigated here is characterized by a multilayer structure. Termination of the diamond surface in aqueous electrolytes by >CH2 and >C=O is supported by electrochemical measurements. A TiC-layer is formed at the phase boundary between the diamond and the titanium. The electrode shows high overvoltages in aqueous electrolytes (eta between 1 and 2 V) for cathodic H-2 and anodic O-2 and Cl-2 evolution. This corresponds to the large band gap of diamond, DeltaE = 5.45 eV. Redox reactions and electrosynthesis at these novel electrodes are briefly reviewed.