<jats:p> The development of an energy storage system with abundant elements is a key challenge for a sustainable society, and the interest of Na intercalation chemistry is extending throughout the research community. Herein, the impact of Ti integration into NaMnO <jats:sub>2</jats:sub> in a binary system of <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>x</mml:mi> </mml:math> </jats:inline-formula> NaMnO <jats:sub>2</jats:sub> –( <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mo>–</mml:mo> <mml:mi>x</mml:mi> </mml:math> </jats:inline-formula> ) TiO <jats:sub>2</jats:sub> ( <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0.5</mml:mn> <mml:mo>≤</mml:mo> <mml:mi>x</mml:mi> <mml:mo>≤</mml:mo> <mml:mn>1</mml:mn> </mml:math> </jats:inline-formula> ) is systematically examined for rechargeable Na battery applications. Stoichiometric NaMnO <jats:sub>2</jats:sub> , which is classified as an in-plane distorted O <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow /> <mml:mrow> <mml:mo>′</mml:mo> </mml:mrow> </mml:msup> </mml:math> </jats:inline-formula> 3-type layered structure, delivers a large initial discharge capacity of approximately 200 mAh g <jats:sup>-1</jats:sup> , but insufficient capacity retention is observed, most probably associated with dissolution of Mn ions on electrochemical cycles. Ti-substituted samples show highly improved electrode performance as electrode materials. However, the appearance of a sodium-deficient phase, Na <jats:sub>4</jats:sub> Mn <jats:sub>4</jats:sub> Ti <jats:sub>5</jats:sub> O <jats:sub>18</jats:sub> with a tunnel-type structure, is observed for Ti-rich phases. Among the samples in this binary system, Na <jats:sub>0.8</jats:sub> Mn <jats:sub>0.8</jats:sub> Ti <jats:sub>0.2</jats:sub> O <jats:sub>2</jats:sub> ( <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>x</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0.8</mml:mn> </mml:math> </jats:inline-formula> ), which is a mixture of a partially Ti-substituted O <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow /> <mml:mrow> <mml:mo>′</mml:mo> </mml:mrow> </mml:msup> </mml:math> </jats:inline-formula> 3-type layered oxide (Na <jats:sub>0.88</jats:sub> Mn <jats:sub>0.88</jats:sub> Ti <jats:sub>0.12</jats:sub> O <jats:sub>2</jats:sub> ) and tunnel-type Na <jats:sub>4</jats:sub> Mn <jats:sub>4</jats:sub> Ti <jats:sub>5</jats:sub> O <jats:sub>18</jats:sub> as a minor phase elucidated by Rietveld analysis on both neutron and X-ray diffraction patterns, shows good electrode performance on the basis of energy density and cyclability. Both phases are electrochemically active as evidenced by <jats:italic>in situ</jats:italic> X-ray diffraction study, and the improvement of reversibility originates from the suppression of Mn dissolution on electrochemical cycles. From these results, the feasibility of Mn-based electrode materials for high-energy rechargeable Na batteries made from only abundant elements is discussed in detail. </jats:p>