Novel microgels composed of acrylaic acid and multifunctional cross-linkers, acrylate/methacrylate cross-linkers, were synthesized via thermal initiated free radical precipitation polymerization in organic solvents. The effect of cross-linker functionality, on the properties of microgels was investigated. Results showed both the solvent absorbency and apparent viscosity depend on the network structure, the crosslinker functionality and number of hydrophobic groups. Gel content indicated more reactivity of acrylate than methacrylate cross-linkers. A linear relation exists between elastic modulus (G') and functionality (f). Also the results suggested an equation that confirmed a direct relationship between glass transition temperature (T-g) and (f). The rotational and apparent viscosity results supported the thickening properties of the microgels. Based on the observations, it is concluded that trifunctional AC cross-linker (TMPTA) choose as an improvement of thickening properties over another cross-linkers. (C) 2012 Elsevier Ltd. All rights reserved.