Fe-substituted Li2MnO3 (Li1+x (Fe y Mn1−y )1−x O2, 0≤ x ≤1/3, 0.3≤ y ≤0.7) was synthesized using a combination of coprecipitation, hydrothermal, and heat-treatment methods. It exhibits high initial specific capacity greater than 200mAhg−1 and small capacity, which fades up to the 50th cycle (>150mAhg−1 at the 50th cycle) under electrochemical cycle testing at 60°C. The attractive electrode properties appeared by controlling the chemical composition (x >0.05, 0.3≤ y ≤0.5) and high specific surface area (>20m2 g−1). The Fe-substituted Li2MnO3 is an attractive candidate as a novel 3V-class positive electrode material.