The book presents important information about creation of models of solvent influence on solute behaviour. The authors explain linear free energy (LFE) relationships in chemistry of solutions and application of LFE in chemical kinetics. The scope includes haemolytic, heterolytic and catalytic reactions with special emphasis on the environment effect on complexes with hydrogen bond and charge transfer. Gas adsorption and solubility of solids as well as interaction of phases are discussed. Application of LFE equations to adsorption and chromatography, swelling of polymers and diffusion are discussed as well.