In hydroxylated poly(styrene-b-butadiene-b-styrene) (HO–SBS) micelle, ZnS/CdS composite nanocrystals were prepared by adding Cd2+ ions and Zn2+ ions to the system sequentially. The resulting composites were identified with elemental analysis, transmission electron microscopy, x-ray diffraction, surface photovoltage spectroscopy, and electric field induced surface photovoltage spectroscopy.