AbstractThe origin and role of nonequilibrium in chromatography is first described, followed by a discussion of the nature of the theoretical problem. The generalized nonequilibrium theory is then developed, leading to an equation for the dispersion of chromatographic zones. It is shown how the generalized nonequilibrium theory can be applied to the special cases of chromatography ‐ particularly adsorption, partition, combined adsorption and partition and diffusion in the mobile phase. The difficulties of comparing theory and experiment are then described, emphasizing those few cases where a quantitative comparison has been possible. A particularly good comparison, obtained with glass bead columns, gives strong support to the theory. It is concluded that such quantitative theory can be applied in two principal ways ‐ to enable the study of physical processes by chromatography and to lead to new chromatographic systems capable of separating substances more efficiently than ever bef