Tunnel-structured Na0.5Mn0.5Ti0.5O2 has been synthesized with a simple solid-phase reaction route as highly stable Na-storage cathode for aqueous sodium-ion batteries (SIBs). Combined chracterizations of X-ray diffraction, scanning electron microscope and electrochemical measurements reveal that the material is mainly composed of rod-shaped particles with a diameter of 500nm and a length of ~5μm. During Na extraction/insertion process, it undergoes a single-phase reaction mechanism in the potential range of 0–1.0V(vs Ag/AgCl), showing a reversible capacity of 46mAhg−1 at a current density of 30mAg−1 and an average operating potential of 0.41V. In particular, excellent cycling performance is achieved owing to the favorable tunnel channel and robust structural framework, with a capacity retention of 95% after 100cycles. The finding in this study demonstrates application potential of the Na0.5Mn0.5Ti0.5O2 material as cathode for low-cost, long-cycling aqueous SIBs.