In this article, we studied the adsorption of 4-tert-butylpyridine (TBP) on the nanocrystalline TiO 2 (anatase) powder by Raman, IR and XPS. In Raman spectra, the free TBP and physisorbed TBP showed the totally symmetric ring breathing mode at 996cm −1 and the vibration of the trigonal symmetry ring stretching mode was too weak to identify, while the coordinated TBP produced the characteristic trigonal symmetry ring stretching mode at 1022cm −1 and the vibration of the totally symmetric ring breathing mode shifted from 996 to 1007cm −1 . From Raman spectra of dye-sensitized solar cells in situ, the Raman line at 167–169cm −1 should be assigned to the formation of TBP·I 2 or iodine adsorbed on the dye. Since there were significant differences from 100 to 300cm −1 , we suggested that TBP, besides the adsorption on TiO 2 , can also remove iodine adsorbed on the dye to suppress the rate of interfacial electron transfer from the conduction band of TiO 2 to iodine.