ZnO micrometer-sized rods with tunable aspect ratios and 3D hollow spherical superstructures are selectively fabricated by a simple poly(sodium 4-styrene-sulfonate) (PSS)-mediated hydrothermal crystallization and assembly strategy. When PSS concentration is relatively low (0-0.5 gL), the aspect ratios of as-obtained microrods steadily decrease with increasing PSS concentration due to the selective adsorption of PSS on the polar ZnO (001) crystal plane. When PSS concentration is relatively high (1 gL), 3D nanosheets-built hollow microspheres form probably due to the organic-inorganic interfacial cooperative assembly. Raman, photoluminescence and UV-vis diffuse reflectance spectra show that the optical properties of as-obtained ZnO microstructures are highly related to their specific morphologies. (c) 2008 Elsevier Inc. All rights reserved.