Potassium tetratitanate (K2Ti4O9) has been synthesized by solid state method using K2CO3 and TiO2, and studied as an anode material for potassium ion batteries for the first time. A discharge capacity of 80 mAh g(-1) has been obtained at a current density of 100 mA g(-1) (0.8 C rate) and 97 mAh g(-1) at 30 mA g(-1) (0.2 C rate), initially. The discharge capacity is stable at low rates of cycling. The uptake of K+ on charging K2Ti4O9 electrodes is quantitatively studied. The proposed mechanism of charging involves reduction of two Ti ions from 4+ oxidation state to 3+ oxidation state, which facilitates insertion of two K+ ions per formula unit. The rate capability experiments suggest that K2Ti4O9 is capable of undergoing charge-discharge cycling at high rates (up to 15 C rate), but with a low discharge capacity. Thus K2Ti4O9 is a promising anode material for future K-ion batteries. (C) 2016 The Electrochemical Society. All rights reserved.