The electrochemical behavior of the three new vanadium oxides (MyH1-yV3O8)-O-v (M = Li, Na, K; y = 0.6-0.9) towards lithium insertion was studied. For each compound. the main insertion phenomena, and the lithium amount which can be inserted, were determined from galvanostatic studies performed at different rates. In order to better explain the differences between the compounds, the galvanostatic intermittent titration technique was used and chronoamperometry experiments were performed. Cyclability studies have shown that the performances of M0.6H0.4V3O8 (M = Li, K) are not better than those of H2V3O8. On the contrary, Na0.9H0.1V3O8 presents very interesting lithium insertion properties, with a specific capacity of 215 mAh g(-1) in the 1.5-4 V voltage range at C/10, and a capacity loss at the 40th cycle remaining smaller than 2.5%. Na0.9H0.1V3O8 is therefore a good candidate as positive electrode material for rechargeable lithium batteries.