A series of Pd and Pd/Au alloy nanoparticles (NPs) with narrow size distribution were encapsulated or stabilized by G4-poly (amido-amine) (G4-PAMAM, G represents the generation) planted in SBA-15. Monodisperse NPs are uniformly distributed in channels of SBA-15 as observed by TEM images. HRTEM, ICP and EDS results confirm the alloy structure of bimetallic NPs. A combination of N-2 adsorption-desorption analysis, ICP and GC was used to optimize the best amount of metal precursors to form catalysts. The as-prepared catalyst manifests outstanding activity and recyclability in microwave-assisted Suzuki-Miyaura coupling reaction when compared with commercial Pd/C. Meanwhile, Pd/Au alloy NPs exhibit higher activity than monometallic ones in catalyzing the coupling between aryl bromide/aryl chloride and arylboronic acid. The mechanism of the improvement of catalytic performance is discussed. (C) 2010 Elsevier Inc. All rights reserved.