In this book, water-dimethylsulfoxide (DMSO)-cellulose and water-acetonitrile (AN)-cellulose systems are studied. The sorption isotherms of the components on cellulose from water-organic mixtures are obtained, immersion heats of cellulose in water-DMSO and water-AN mixtures and heats of phenol dissolution in the above-mentioned mixtures are measured. The thermodynamic characteristics of phenol dissolution as well as sorption character on cellulose change drastically at concentrations corresponding to change of character of cluster formation in water-DMSO and water-AN mixtures. It is shown that sorption of the components of binary water-organic mixtures and phenol sorption from these mixtures on cellulose depend on the intermolecular interactions in the water-DMSO and water-AN solutions.