Abstract: A fluorophotometric method for the determination of ampicillin was established in this paper.The method was based on that the ampicillin was degradated under conditions of pH 9.0 in an ammoniacal buffer medium and of the presence of Cu(Ⅱ) as catalyst and heating with boiling water bath,and the fluorescence intensity of the degradation product was determined fluorophotometrically.The activation energy of 34.88 kJ·mol-1 and the reaction rate constant of 4.68 h-1 were found.A linear relationship between the fluorescence intensity and ampicillin concentration in range of 1.5×10-7-3.0×10-6mol·L-1 was obtained.Detection limit was 4.0×10-8mol·L-1 and recoveries were in the range 95.3%-101.4%.The method has been applied to the determination of ampicillin in capsules and urine samples.