With the continuing increase in power dissipation requirements of electronic devices, there is a need to develop new thermal interface materials (TIM) with much higher thermal conductivity (K) than that available from conventional TIMs. Recently, liquid phase sintering (LPS) has been proposed as a new paradigm for designing next generation composite-solder TIMs with a radically different microstructure from those of conventional solder-TIMs. LPS metallic composites are also attractive as phase change materials (PCM) for thermal energy storage, where the latent heat absorbed by the one of the phases upon melting can be stored for later retrieval and/or conversion to other forms of energy. The principal advantage of metallic PCMs over other materials include: (i) much greater energy storage per unit volume than organic PCMs; and (ii) much higher thermal conductivity than both organics and inorganic salt PCMs, which allow rapid heating and energy capture. This paper presents recent results on the development of metallic TIM and PCMs for energy storage, processed by LPS of a high melting phase (HMP) with a low melting phase (LMP). A discussion of processing issues, resultant properties, and modeling results expounding the benefits of these materials is presented.