Adsorption of N,N-dimethylformamide (DMF) molecules on the surface of ZnS nanocrystallites was investigated by in situ Fourier transform IR and NMR spectroscopy in acetonitrile (AN)/methanol mixture solution. The C=O stretching vibration (v(C=O)) of DMF molecule shifted to a lower wavenumber when adsorbed on ZnS nanocrystallites. Their peak wavenumbers and intensities reflect the strength of interaction in DMF-ZnS surface bonding and a number of adsorbed DMF molecules. H-1 NMR measurements of this system also revealed strong interaction of DMF molecules with the surface of ZnS nanocrystallites. The surface interaction of DMF molecules was dependent on the coexistent counteranions in solution. DMF molecules coordinate more effectively to the surface of ZnS nanocrystallites prepared from Zn(ClO4)(2). 6H(2)O than that prepared from Zn(OAc)(2). 2H(2)O. These results agree well with the characteristics of interacting structure of DMF molecule observed by in situ extended X-ray absorption fine structure analysis reported previously.