超细粒子因其具有明显的体积效应和表面效应，在催化、功能材料等领域得到了广泛的应用［１～３］，这在一定程度上促进了其制备科学的发展。超细粒子的制备方法较多，通常分为物理法、化学法和综合法三大类。其中化学沉淀法是一种最经济、最常用的制备超细氧化物粉体的方法。目前，采用沉淀法制取ＣｕＯ系列催化剂多以Ｃｕ（ＮＯ３）２ 为原料，而以其它二价铜盐为原料来考察制备条件对所得粉体催化活性影响的研究报道尚少［４，５］。为此，我们以ＣｕＣｌ２ 为原料，采用沉淀法制备ＣｕＯ 催化剂，结果意外地得到了一种对分解Ｈ２Ｏ２ 具有极高催化活性的Ｃｕ２（ＯＨ）３Ｃｌ－ＣｕＯ超细粉体，并发现反应液ｐＨ 值是控制该粉体物相、粒子大小及催化活性的关键。此结果为Ｃｕ 系催化剂的研究、开发，特别是对Ｏ２ 电极催化材料的制备提供了有价值的信息 Ultrafine particles have been widely used in many fields such as catalysis and functional materials due to their obvious volume effect and surface effect [1 ~ 3], which promoted the development of their preparation science to a certain extent. Preparation of ultrafine particles are more, usually divided into physical, chemical and comprehensive law three categories. Among them, chemical precipitation is one of the most economical and popular methods for preparing ultrafine oxide powders. At present, the CuO catalyst prepared by precipitation method mostly uses Cu (NO3) 2 as raw material, while other divalent copper salts as raw materials to investigate the preparation conditions on the catalytic activity of the resulting powder is still little reported [4,5]. For this reason, we use CuCl2 as raw material to prepare CuO catalyst by precipitation method. As a result, a Cu2 (OH) 3Cl-CuO superfine powder with high catalytic activity for decomposition of H2O2 was unexpectedly obtained. It was found that pH value of the reaction solution It is the key to control the phase, particle size and catalytic activity of the powder. This result provides valuable information for the research and development of Cu-based catalysts, especially for the preparation of catalytic materials for O2 electrodes