A serious of CoFe hydrous oxide nanoparticles (Co1-zFezOxHy NP [z = 0-1]) were synthesized by stirring CoCl2 and FeCl2 in aqueous KOH solutions for 0.5 hours, and the resulting nanoparticles are active electrocatalysts for water oxidation reaction (WOR) in alkaline solutions. The Co0.75Fe0.25OxHy NP, which are the most active electrocatalysts, have a layered double hydroxide (LDH) structure, with the average particle sizes about 16 nm. When using Ni foam as the substrate, the electrode with Co0.75Fe0.25OxHy NP as catalysts exhibited an overpotential of 284 mV for WOR in 1 M KOH at 10 mA cm(-2). The Tafel slope was 43 mV dec(-1), and the TOF was 1.30 s(-1) at 350 mV overpotential (loading Co + Fe = 0.133 mg cm(-2)). The Co0.75Fe0.25OxHy NP are robust toward long-term galvanostatic test and showed less than 2% dissolution in 10 hours. Preliminary kinetic study suggests that the presence of Fe in Co1-zFezOxHy NP alters the WOR mechanistic pathways. The increased number of electrochemically active sites endowed by the LDH structure and the electronic interactions between Co and Fe as suggested by XPS, both contribute to the enhanced WOR activity.