Well-defined boehmite (γ-AlOOH) nanomaterials with regular shapes, which include nanorods, nanobelts, and nanoplates, were prepared by hydrothermal reactions of γ-AlOOH nanoparticles, to which H 2 SO 4 , CH 3 COOH, and HCl were added to regulate the shape of the products. The formation of the nanomaterials with different shapes could be attributed to adsorption of SO 4 2-, CH 3 COO -, and Cl -on the crystal planes, which affected the oriented aggregation of the raw γ-AlOOH nanoparticles and the growth of the aggregates.