Abstract: Electrochemical behavior of pentamidine (PTM) was studied by cyclic voltammetry.As shown by experimental results,in a phosphate buffer of pH 8.5,a sensitive reduction wave produced by PTM was observed at the potential -1.56 V (vs.SCE),which is proved to be a catalytic hydrogen wave.Linear relationship was held between peak current of the reduction wave and concentration of PTM in the range of 2.0×10-5-8.0×10-4mol·L-1 (r=0.997 3).Detection limit of the method was found to be 1.6×10-5mol·L-1.Based on these facts,a derivative pulse voltammetric method of direct determination of PTM without necessity of separation was proposed.Recovery test was performed by addition of standard PTM solution to a urine sample,and the results obtained were in the range of 95.1%-103.8%.