The relation between the non-equilibrium thermodynamics and kinetic th
eory of rarefied gases is discussed. The phenomenological equations of
generalized non-equilibrium thermodynamics are formulated using the f
undamental relations of kinetic theory. Using the approach developed,
the non-equilibrium thermodynamics of a multicomponent gas mixture is
formulated for the moment method and Burnett approximation and the bou
ndary conditions including the slip and jump effects are derived for s
lightly rarefied gases. Application to transport processes in disconti
nuous systems and gas flows over solid bodies is also made.