Kinetic and thermodynamic interaction properties between dialkyl phthalate test compounds and a polyolefin polymer were examined via a permeation-cell experimental design. Disappearance and appearance rates of solute in the receptor and donor solutions, as well as the equilibrium composition of the test system, are used to determine sorption and diffusion coefficients and the solute/polymer equilibrium binding constant. Sorption rate constants and diffusion coefficients exhibit Arrenhius-type behavior. The binding constants obtained correlate well with the solute's octanol-water partition coefficient. The kinetic and thermodynamic data generated combine with proposed interaction models to identify solute/polymer interactions (binding and leaching) pertinent to evaluating container/solution compatibility for parenteral products.