In order to fabricate lightweight flaky electromagnetic particles efficiently, the diatomite was used as the forming template to which the CoNiP coating was deposited by an electroless plating technique. The electroless plating of CoNiP on diatomite was accomplished with the coupling processing before the activation, in which 3-aminopropyltriethoxysilane (APTES) was used as the coupling agent. The effect of coupling processing on the activation and electroless plating of diatomite was characterized by SEM, FT-IR and EDS analysis. The results indicated that with coupling processing before activation, the catalytic effect was improved remarkably than that of direct colloidal palladium activation, which resulted in superior electroless plating on diatomite, even on the surface of submicron holes. The XRD analysis showed that the CoNiP coating was a transitional structure between crystal and amorphousness. The measurement of complex permeability and permittivity in the range of 2-18 GHz suggested that the micro flaky electromagnetic particles had promising electromagnetic properties. (C) 2012 Elsevier B. V. All rights reserved.