This paper is concerned with the specific heat and thermal conductivity of metals at cryogenic temperatures. A review of previous studies is complemented by the author's experience. Two internal energy forces affect specific heat—lattice interactions and electronic interactions. Since the lattice specific heat is related to T³, it is very small at very low temperatures. The total conductivity of a metal is the sum of the electron thermal conductivity and the lattice thermal conductivity. Two factors that reduce electronic thermal conductivity are scattering of conduction electrons by thermal vibrations in the lattice, and scattering of electrons by defects and impurities present in the lattice. It is not yet possible to accurately predict thermal conductivity from fundamentals, but it is possible to make adequate predictions from thermal properties or electrical resistance of similar materials.