Resistive random access memory (RRAM) is one of the most promising candidates as a next generation nonvolatile memory (NVM), owing to its superior scalability, low power consumption and high speed. From the materials science point of view, to explore optimal RRAM materials is still essential for practical application. In this work, a new material (Bi, Mn)Ox (BMO) is investigated and several key performance characteristics of Pt/BMO/Pt structured device, including switching performance, retention and endurance, are examined in details. Furthermore, it has been confirmed by high-resolution transmission electron microscopy that the underlying switching mechanism is attributed to formation and disruption of metallic conducting nanofilaments (CNFs). More importantly, the power dissipation for each CNF is as low as 3.8/20fJ for set/reset process, and a realization of cross-bar structure memory cell is demonstrated to prove the downscaling ability of proposed RRAM. These distinctive properties have important implications for understanding switching mechanisms and implementing ultralow power-dissipation RRAM based on BMO. •Self-formed conductive nanofilaments in BMO show ultralow-power memory feature.•The feature of 10nm in diameter and an average 20-30nm spacing of CNFs suggests the compatibility with the current CMOS technologies.•Power dissipation for each CNF is as low as 3.8/20fJ for set/reset process•A realization of cross-bar structure memory cell is demonstrated to prove the downscaling ability of proposed RRAM. © 2015 Elsevier Ltd.