The present study describes the fabrication of a sensitive amperometric sensor for the determination of persulfate. The immobilization surface was prepared by modifying a glassy carbon (GC) electrode with a nanocomposite containing ruthenium oxide (RuOx) nanoparticles and thionine (TH) or celestin blue (CB). The modified electrodes indicated excellent electrocatalytic activity toward persulfate reduction at a potential of +0.1 V. The proposed sensor showed detection limits of 1.46 mM for the GC/RuOx/TH modified electrode and 2.64 mM for the GC/RuOx/CB modified electrode. The sensitivities were obtained as 3 nAmM1 at a concentration range of 10 mM to 11 mM for the GC/RuOx/TH modified electrode and 1 nAmM1 at a concentration range of 10 mM to 6 mM for the GC/RuOx/CB modified electrodes
