CeB6 powder was prepared via combustion synthesis (CS) and mechanochemical processing (MCP) methods starting from CeO2, B2O3 and Mg powder mixtures. In CS, reactant mixtures were ignited in a preheated pot furnace under argon atmosphere. Products contained CeB6, MgO and Mg3B2O6, as revealed by X-ray diffraction analysis. After leaching in 1 M HCl for 15 h, MgO was removed but Mg3B2O6 could not be removed from the products. Ball milling of products in ethanol prior to leaching made the removal of Mg3B2O6 possible by leaching. Yield of CeB6 was 68.6% in CS. MCP was performed in a stainless steel vial with a planetary ball mill at 300 rpm for 30 h. MCP products contained CeB6, MgO and small amount of Fe. Leaching in 1 M HCl for 30 min was sufficient to remove MgO. Yield of CeB6 was 84.4% in MCP. According to scanning electron microscopy examinations, particles of CeB6 prepared by CS and MCP had submicrometer size. Average particle sizes were determined as 290 nm and 240 nm, respectively.