This is the first comprehensive monograph on a new thermodynamic theory that goes beyond the classical theory of irreversible processes. In contrast to the classical approach, the local equilibrium hypothesis is abandoned. The basic variables describing the system are no longer the equilibrium conserved variables: the latter are complemented by non-equilibrium quantities, such as the heat flux, the viscous pressure tensor, the matter flux, the electric current flux, etc. The claims made for extended thermodynamics are confirmed by the kinetic theory of gases and statistical mechanics. The book covers a wide spectrum of applications such as hyperbolic heat conduction, rheological models, waves in fluids, generalized hydrodynamics, phase diagrams of solutions under shear, non-Fickian diffusion, electrical systems, and a relativistic formulation including some cosmological applications. The book also contains a wide discussion of the foundations and the scope of the current theories on non-equilibrium thermodynamics (classical irreversible thermodynamics and rational thermodynamics). The present edition reflects new developments in the theory and applications, adds new problems and provides a more detailed comparison with other fields of active research. It contains one hundred thirty proposed problems, whose detailed solutions, as well as wide bibliography on extended irreversible thermodynamics and related topics,may be unloaded from the www.uab.es/dep-fisica/eit website.