Abstract: In an acidic medium of pH 3.2, sensitization effect of dye azure I on the fluorescence of catechol was observed obviously. The magnitude of increase in fluorescence intensity was found to keep linear relationship with the concentration of catechol in the range of 0.075-30 μmol·L-1; when measured at the wavelength of 343.0 nm (λem). Detection limit (3s/k) of the method was found to be 7.51 nmol·L-1. The proposed method was applied to the analysis of water sample, giving values of recovery obtained by standard addition method in the range of 97.0%-104% with RSD′s (n=5) in the range of 2.8%-3.9%.