Liquid chromatography (LC) is a widely used technique for the analysis of non-volatile analytes in mixtures of interest in a wide variety of fields, including pharmaceuticals, energy, the environment, and materials, among many others. One tool for rationalizing and understanding the retention of molecules has been the development of numerous models that express the retention factor (k) as a function of the mobile phase composition . These models include the linear solvent strength (LSS) model, , the Neue-Kuss (NK) model , the quadratic model , an enhanced LSS model that allows for variations in the elution degree , the Jandera model , as well as many others . These models have all been successfully used in many situations, depending on the mode of chromatography and the range of mobile phase compositions. One issue with many of these models is the presence of a parameter in the model that represents the retention factor of the solute in the pure weak solvent (or at other limiting conditions; in reversed-phase LC (RPLC), this is a purely aqueous phase). However, the experiments that produce the data used in fitting these models usually are carried out at higher organic mobile phase compositions. This means that the resulting fits to models almost always involve extrapolation to the weak solvent condition, the results end up being highly dependent on the initial guesses used in the fit routine, and this all leads to ill-conditioned matrix inversions during the fitting process and unreliable parameter estimates . Peris-García et al. recently described the reparameterization of many of these models, so that instead of using the kw parameter within the model, a kref parameter was used, corresponding to the retention factor at an organic composition of ref . These authors proposed using a ref corresponding to the organic phase composition for the maximum retention factor in the experimental design. In the present work, we extend this re-parameterization strategy to the NK model, which is frequently use for fitting reversed phase LC retention factors . We will show that this improves the results obtained in the fitting procedure.