Monodisperse trimetallic CoAgPd alloy nanoparticles (NPs) were synthesized by a controlled co-reduction of cobalt (II) acetylacetonate, silver nitrate and palladium acetylacetonate in oleylamine at 90 degrees C using 2-methylpyridine borane as the reducing agents. This is the first time using amine borane as the reducing agent to synthesize non-noble metal contained monodisperse trimetallic alloy NPs at relatively low temperature. The 2.8 nm monodisperse CoAgPd NPs were further assembled on graphene by a simple solution-phase self-assembly method, and tested for catalytic dehydrogenation of formic acid at room temperature. Unexpectedly, the introducing of small amount of cobalt can significantly enhance the catalytic activity and selectivity. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.