Aluminum hydroxide sol was prepared by the sol-gel method. Dynamic moduli such as storage and loss moduli were measured to investigate the relative dominance of elastic and viscous contributions to the viscoelastic response of aluminum hydroxide sol during sol-gel transition. The loss modulus, a measure of viscous response, is larger than the storage modulus, a measure of elastic response, for the sols of low particle concentrations. But at a high particle concentration above 15.3wt%, the storage modulus is found to be larger than the loss modulus. This inversion from a viscous to an elastic response with the increase of particle concentration is attributable to the formation of gel structures by the aggregation of dispersed particles.