Alkali metal thermoelectric converter (AMTEC) is a high-efficiency device for directly converting heat into electricity. The converter operates as a thermally regenerative electrochemical cell by expanding alkali metal (as the name suggests) vapors through the pressure differential across an electrolyte membrane. Although AMTEC technology is still being developed, laboratory devices have achieved efficiencies as high as 19% and system design studies indicate that efficiencies as high as 35–40% or more may be possible. The converter provides all the advantages of a static power system (low or no vibration, redundancy, no wear and tear) at relatively high efficiencies normally achievable only by dynamic systems. Small system designs using AMTEC have shown 27% cell and 23% system efficiencies, whereas laboratory experiments with developmental cells have achieved 16% efficiencies. Alkali metal thermoelectric converter requires heat energy input at modest temperatures, and not at a specific wavelength, and it is easily adapted to any heat source in any state, including nuclear reactor, radioisotope, concentrated solar power, external combustion, and heat rejected from other devices. This adaptability makes AMTEC very attractive for many potential space and terrestrial applications. Investigation of detailed models of AMTEC that allow better prediction of converter behavior, and experimental investigation of material behavior in AMTEC cells to better understand the interaction and degradation mechanisms that affect cell performance are currently in progress. Objective: The objective of this article is to review the design of a reliable and efficient energy conversion device for advanced space and terrestrial power generation. In that effort, the uses and advantages of AMTEC cell are presented by explaining the working principle of its main components in a simple nonmathematical manner.