Adsorption of poly(ethylenimine) and complexes of poly(ethylenimine) with copper(II) ions on copper(II) oxide powder has been investigated, The rate of adsorption and reaction between poly(ethylenimine) and CuO is very fast. The desorption rate of the complex of poly(ethylenimine) with copper(II) ions is slower and decreases when the initial polymer concentration is decreased, The desorption rate passes through a minimum when the initial concentration of CuO powder in the mixture increases. A mathematical model of polymer adsorption and desorption is proposed.