Abstract: In a supporting electrolyte containing NaOH , an irreversible reduction peak ofdipyridamole( DPD ) was found by linear-sweep Voltammetry at Hg electrode. The peak shows apotentlaI Of—1.39 V(us Ag/AgCl)and adsorptive characteristics.When the concentration of DPDis sufficiently low ,the sweep rate sufficiently rapid and the accumulation time sufficiently long , thepeak current is almost totally contributed by the reduction of adsorbed DPD. The experiments of phaseselective AC voltammetry indicate that the adsorbed species is most probably neutral DPD molecule.The number of electrons transferred per DPD molecule,n,is 4 and the value of an_a of the irreversibleadsorptive system of DPD is l.72.The mechanism of electrochemical reduction of DPD at HgeIectrode was explored. The optimized condition for measuring trace amount of DPD by adsorptivestripping voItammetry was established.