The silver nanoparticles with about 10 nm diameter were immobilized onto the halloysite nanotubes (HNTs) via the in situ reduction of AgNO3 by polyol process. The silver nanoparticles supported halloysite nanotubes (Ag/HNTs), with Ag content of about 11%, were used for the catalyzed reduction of 4-nitrophenol (4-NP) with NaBH4 in alkaline aqueous solutions. The effect of the reduction of 4-NP catalyzed by the catalysts in the presence of variable concentration NaBH4 was investigated. It was found that the reduction rate increased with the increasing of the amounts of NaBH4. And the larger amounts of NaBH4 reduced the induction time. (C) 2008 Elsevier B. V. All rights reserved.