Although the importance of interactions between organic compounds and soil organic matter (SOM) can hardly be overestimated, sorption mechanisms are far from understood due to the complexity of the chemically and physically heterogeneous SOM sorbent phase. Structure of the SOM sorbent can be changed drastically as its hydration status varies under different environmental conditions. To understand the SOM hydration effect on sorption, insights into SOM-organic compound sorption mechanisms are required, and, vice versa, comprehending the effect of hydration (or solvation, in a wider sense) on organic compound sorption by SOM is helpful in delineating sorption mechanisms in such a complicated and important environmental sorbent. On the basis of a series of sorption studies, we present a concept elucidating the relationship between the hydration effect on organic compound sorption by SOM, and sorption mechanisms. The central point of this concept is based on the observation that for certain compounds, sorption strongly increases upon SOM hydration (or solvation by strongly interacting organic solvents). This phenomenon is interpreted by considering the SOM phase to be represented by a set of distributions of various inter- and intra-molecular non-covalent links and contacts. Hydration (solvation) of SOM is associated with partial disruption of the linkages and SOM swelling, resulting in some SOM structure opening. The “quasi-equilibrium” of this link disruption and the extent of the opening of the SOM structure shift as a function of organic compound sorption, and are assisted by solvation of disrupted link fragments, thus involving cooperation between solute and solvent molecules. Depending on the ability of sorbate molecules to interact with SOM and to compete with water molecules for sorption sites, there will be a trade-off between solvent-assisted penetration of organic compound molecules into SOM linkages, versus competition between sorbate and solvent molecules for new sites at those disrupted contacts.