Many problems in electrocatalysis involve distribution of adsorption energies. Similarly, electrochemical impedance spectroscopy often involves distributed elements. Such problems are described by Fredholm integral equations and the underlying distribution functions may be solved using regularization techniques. A software package developed recently was used to determine the distribution function and the regularization parameters. Our studies show that it is relatively easy to obtain the adsorption energy distribution functions In simple cases. Comparison of the hydrogen adsorption on polycrystalline and monocrystalline (531) platinum shows similarities in the adsorption energies on both surfaces. Continuous (constant phase element and discontinuous (fractal model) time constant distribution functions in the impedance were well reproduced, but in the more complex case (porous electrode) the method is more limited.