The interaction between colloidal AgTiO 2 nanoparticles and bovine serum albumin (BSA) was studied by using absorption, steady state, time resolved and synchronous fluorescence spectroscopy measurements. Absorption spectroscopy proved the formation of a ground state BSA⋯AgTiO 2 complex. Upon excitation of BSA, colloidal AgTiO 2 nanoparticles effectively quenched the intrinsic fluorescence of BSA. The number of binding sites (n=1.06) and apparent binding constant (K=3.71×10 5 M −1 ) were calculated by the fluorescence quenching method. A static mechanism and conformational changes of BSA were observed.