Because of low cost, low toxicity and simple synthesis method, transition metal oxides have been regarding as promising candidate materials for sodium ion batteries (SIB). In this work, O3-type layered oxide of Na0.9Ni0.45Ti0.55O2 was synthesized and evaluated as a novel bipolar material for SIB. It is found that, as a cathode material, the initial discharge capacity can reach around 109.6 mAh g(-1) at 0.05C. When severing as anode material, it displays a reversible capacity of 44.5 mAh g(-1). The bipolar character is attributed to two different redox active substances in Na0.9Ni0.45Ti10.55O2 with the high-voltage redox couple Ni4+/Ni2+ and the low-voltage redox couple Ti4+/Ti3+. This study provides new insights into the design and synthesis of novel electrode materials for SIBs and some other applications.