Most experimental polymerization kinetic data are in the form of degree of polymerization versus time plots. However, to explore kinetic models it is more useful to have the data as polymerization rate versus degree of polymerization plots. Converting degree of polymerization into rate is an ill-posed problem in that if inappropriate methods are used the noise in the data will be amplified, leading to unreliable results. This paper describes a procedure, based on Tikhonov regularization, to perform this conversion. The procedure is independent of kinetic models and keeps noise amplification under control. Its performance is demonstrated using several sets of published polymerization kinetic data. In each case the computed rates are used to determine the parameters in the rate expression proposed in the original papers. Modified rate expressions will also be explored. The ease with which such investigations can be performed highlights the advantages of this new procedure. (C) 2004 Wiley Periodicals, Inc.