The simplest experimental method to determine the Hansen solubility parameters (HSPs) for a polymer is to evaluate whether or not it dissolves in selected solvents. Those solvents dissolving the polymer will have HSPs closer to those of the polymer than those that do not. A computer program or graphical method can then be used to find the HSP for the polymer. In this work, an improved method for calculating the HSP of polymers, based on the Nelder-Mead optimization algorithm, is presented. The results of this program fit the data very well. (C) 2006 Wiley Periodicals, Inc. J Appl Polyrn Sci 103: 31-36, 2007