A series of Ni-Cu alloy particles with different atomic ratios of Ni/Cu were prepared by the thermal decomposition of fibrous Ni-Cu oxalate precursors in methane atmosphere. The resulting porous aggregates of Ni-Cu alloy particles showed promising catalytic activities for methane decomposition at temperatures of 700 and 750 degrees C. A Ni-Cu alloy catalyst with 62.5% nickel content was able to achieve the highest methane conversion of about 82% at a reaction temperature of 750 degrees C. The addition of the right amount of copper led to the formation of alloy particles with small crystalline and particle sizes. Unlike the supported catalysts, the self-regulating system of the unsupported catalysts led to the formation of isometric, round catalyst particles which showed stable catalytic activity even at 750 degrees C. The frequent appearance in the supported catalyst system of liquid-like Ni-Cu catalyst at temperatures above 700 degrees C was suppressed in the unsupported Ni-Cu alloy catalyst system. The stability of the catalysts is discussed and a deactivation mechanism is proposed. (C) 2014 Elsevier B.V. All rights reserved.