In-situ Zn K-edge extended X-ray absorption line structure (EXAFS) analysis of colloidal ZnS nanocrystallites (ZnS-DMF, mean diameter 3 nm, hexagonal) prepared by reacting zinc perchlorate (ZnS-DMF-ClO4), zinc sulfate (ZnS-DMF-SO4), of zinc acetate (ZnS-DMF-Ac), with H2S in N,N-dimethylformamide (DMF) was performed to clarify the microscopic surface structure of the nanocrystallites. EXAFS analysis reveals that the zinc atoms on the surface of ZnS nanocrystallites in DMF are solvated by the oxygen atoms of DMF molecules. The structural parameters, such as atomic distances and coordination numbers of the Zn-S and Zn-O shell, depend on the coexistent counteranions of the starting zinc salts. The coordination numbers for the Zn-S shell of ZnS-DMF-SO4 and -Ac are greater than that of ZnS-DMF-ClO4, indicating that ZnS-DMF-ClO4 has zinc atoms which are most efficiently solvated by DMF oxygens on the surface, while ZnS-DMF-SO4 and -Ac have a S-rich surface in DMF. The S-rich surface of ZnS-DMF-SO4 and -Ac well explains the spectral behavior, i.e,, the red sl-Lift of the absorption onsets by the addition Zn2+ ions to the respective ZnS-DMF solutions.