The electrochemical insertion of lithium in the ramsdellite polymorph of titanium dioxide, TiO2 (R), is studied by electrochemical methods. At room temperature the maximal Li uptake under constant current densities of 0.1, 0.5 and 1.0 mA cm(-2) is 0.85, 0.8 and 0.7 Li/Ti, respectively. Between 2.3 and 1.3 V versus lithium, the specific capacity achieved is as high as 285 A h kg(-1) at 0.5 mA cm(-2). This corresponds to 85% of the maximum theoretical capacity (336 A h kg(-1)), which may be reached by incorporation of one lithium per titanium under equilibrium conditions.