The alkali metal thermal to electric converter (AMTEC) is a static energy conversion device of thermal to electric energy using a beta"-alumina solid electrolyte. This paper discusses a thermal design for AMTEC cells, which employ a capillary wick for sodium recirculation. The selection of optimum wick pore size, expected capillary force, and flow resistance data are examined. A thermal analysis program is developed, and heat transfer process and conversion efficiency are discussed. The calculated result indicates wick recirculation-type AMTEC cells, which have single and multiple beta"-alumina tubes, can operate over a temperature range up to 1100 K and the expected conversion efficiency is 20-25%.