Carbon-supported Ni(OH)(2)-MnOx/C composite was synthesized by reducing the amorphous MnO2/C suspension in the presence of Ni2+ with NaBH4. The electrocatalytic activity and stability toward the oxygen reduction reaction (ORR) in alkaline media as well as the physical properties before and after the accelerated aging tests for the Ni(OH)(2)-MnOx/C composite were investigated and compared with those for the MnOx/C and the amorphous MnO2/C through electrochemical techniques, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The Ni(OH)(2)-MnOx/C composite is more active toward the ORR than the MnO2/C and MnOx/C, especially at low overpotentials, with the half-wave potential shifting positively about 0.05 V. Experienced the accelerated aging tests, the ORR limiting current for the Ni(OH)(2) MnOx/C composite just degrades a little, while for the MnO2/C and MnOx/C the ORR limiting currents decrease significantly. Though the more obvious negative shifting of the ORR half-wave potential, the Ni(OH)(2)-MnOx/C composite still processes higher current than those for the MnO2/C and MnOx/C in the mixed kinetic-diffusion control region. After the accelerated aging tests, the electron transfer number of the ORR for the Ni(OH)(2)-MnOx/C composite still closes to four, while for the MnO2/C and MnOx/C, the electron transfer numbers decrease obviously from 3.88 and 3.87 to 3.22 and 3.55, respectively. The results of XRD show that phase transformation for Mn occurs and XPS studies prove that the average valence of Mn decreases for both of the MnO2/C and MnOx/C samples after the accelerated aging tests, but no obvious change occurs for the Ni(OH)(2)-MnOx/C sample. The TEM images before and after accelerated aging tests show that the morphology of the Ni(OH)(2)-MnOx/C keeps unchanged loosely-aggregated floccules, while for the MnO2/C and MnOx/C, the morphology changes from the initial loosely-aggregated floccules and nano-rods to nano-blocks and some branch-like substances, respectively. The addition of Ni(OH)(2) into MnOx plays a significant role in its stabilization. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.