Synthesis of various X-birnessites (X = Na, Al, Mg) was performed from the oxidation of manganese hydroxide by an aqueous permanganate solution, Their structural and electrochemical characteristics are investigated. The influence of the exchanged cations and water content on the galvanostatic cycling curves has been studied. The best results are obtained for Mg-birnessite with a specific capacity of 130 Ah kg(-1) recovered after 20 cycles at a C/20 discharge/charge rate for Mg birnessite. The cycling stability increased with increasing crystal lattice water content of the materials.