Redox behavior and electrocatalytic activities of the Ti/nano\|TiO\-2 electrode were investigated by cyclic voltammetry(CV) and bulk electrolysis. The results indicate that there are two pairs of well\|defined redox peaks for Ti/nano\|TiO\-2 film electrode in the 1 mol/L H\-2SO\-4 and 1 mol/L NaOH at 0.1 V/s corresponding to TiO\-2/ Ti\-2O\-3 and TiO\-2/Ti(OH)\-3 reversible electrode process. In 1 mol/L NaOH medium the peak potential evidently shift to the negative value with \%E\%\+r\-\{1/2\} being -1.38 and -1.72 V(\%vs\%.SCE), and the heterogeneous electrocatalytic reduction activities of TiO\-2/Ti\-2O\-3 redox for \%p\%\|nitrobenzoic acid (PNA) is very high. The indirect electroreduction of PNA to \%p\%\|aminobenzoic acid (PAA) by Ti\+Ⅳ/Ti\+Ⅲ redox system on nanocrystalline TiO\-2 film surface was found, and the electrode reaction mechanism is called electro\|catalytic(EC) mechanism. In the preparative electrolysis, the current efficiency was over 90%.
