Rheological measurements have been performed on a system of a partially hydrolyzed polyacrylamide (HPAM) with Cr(III) as a cross-linking agent. A sol/gel phase diagram of the system has been established The scaling properties of the gel have been investigated varying the cross-link concentration at a fixed polymer concentration, measuring the dynamic storage modulus, G’, after the reaction was completed. The variation of final storage modulus versus Cr(III) concentration is described by the percolation model, giving a scaling exponent for G’ of 1.9. Combining the percolation model description with a traditional kinetic approach for first-order reactions, the kinetics of gelation were determined from measured time dependence of G’. Comparison has been made to measurements by UV-vis spectroscopy on the same systems. The measurement of G’ provides additional mechanistic information about the gelation process. It indicates that the observed biphasic natures of the first-order plots from theology and spectroscopy measurements are due to a side reaction. The cross-linking is believed to proceed through a rate-determining introduction of the first HPAM to Cr(III).