The pharmaceuti-cally active com-pound atenolol,a kind of β-blockers,may result in ad-verse effects both for human health and ecosystems if it is excreted to the surface water resources.To effectively remove atenolol in the environment,both direct and indirect photodegradation,driven by sunlight play an important role.Among indirect photodegradation,singlet oxygen (1O2),as a pivotal reactive species,is likely to de-termine the fates of atenolol.Nevertheless,the kinetic information on the reaction of atenolol with singlet oxygen has not been well investigated and the reaction rate constant is still am-biguous.Herein,the reaction rate constant of atenolol with singlet oxygen is investigated di-rectly through observing the decay of the 1O2 phosphorescence at 1270 nm.It is determined that the reaction rate constant between atenolol and 1O2 is 7.0× 105 (mol/L)-1.s-1 in D2O,8.0×106 (mol/L)-1.s-1 in acetonitrile,and 8.4×105 (mol/L)-1.s-1 in EtOH,respectively.Furthermore,the solvent effects on the title reaction were also investigated.It is revealed that the solvents with strong polarity and weak hydrogen donating ability are suitable to achieve high rate constant values.These kinetics information on the reaction of atenolol with singlet oxygen may provide fundamental knowledge to the indirect photodegradation ofβ-blockers.