We report a facile synthesis of mesoporous alumina catalysts supports which enables control of pore structure, including pore diameter, by controlled hydrolysis of aluminum alkoxides without addition of a template or structural directing agent. By employing low water to alumina molar ratios and varying this ratio from 2 to 15, we are able to synthesize γ-alumina catalyst supports with different pore structures. X-ray diffraction, transmission electron microscopy, nitrogen gas adsorption, and comparative adsorption analysis were performed to determine structures of these materials. After calcination at 700 °C for 2 h, surface areas of these synthesized alumina catalyst supports range from 240 to 320 m²/g, average pore range from 4 to 18 nm, and pore volumes range from 0.4 to 1.6 cm³/g. Accordingly, this synthetic strategy provides a facile route to the controlled synthesis of nanostructured alumina catalyst supports with customized pore structures.