This article reports the selective sensing ability of a newly synthesized calixarene Schiff base (C4TSB) derivative. C4TSB exhibited strong turn-off fluorescence affinity for Hg2+ and Au3+. The selective sensing ability of receptor was investigated in the presence of different co-existing competing ions. The limit of detection for Hg2+ and Au3+ was determined as 1.9 x 10(-5) and 1.0 x 10(-6) M, respectively. Receptor forms 1:1 stoichiometric complex with both metals and their binding constants were calculated as 7.9 x 10(3) M-1 for Hg2+ and 5.7 x 10(3) M-1 for Au3+. Complexes were also characterized through FT-IR spectroscopy.