Crystalline nanosized particles of clathrate-II phases KxGe136 and NaxSi136 were obtained from a dispersion of alkali metal tetrelides in ionic liquids based on DTAC/AlCl3, which were slowly heated to 120-180 degrees C. The nanoparticles are bullet-shaped with typical dimensions of about 40 nm in width and 140-200 nm in length. Detailed structure investigations using high-resolution transmission electron microscopy (HRTEM) and electron holography reveal the crystallinity and dense morphology of the clathrate nanorods.