AbstractAn overall adsorption quantity for a heterogeneous solid is usually expressed by an integral equation, which contains a distribution function that describes heterogeneous properties of this solid. The calculation of this distribution function is an ill‐posed problem. The current article shows that the difficulties arising from the ill‐posed nature of an adsorption equation can be overcome with the regularization method. This work presents general principles of regularization for solving the ill‐posed problems without detailed mathematical considerations. The application of the regularization method to calculate a distribution function from any overall adsorption functions is illustrated with both simulated and experimental adsorption isot