Isotactic polypropylene (iPP)/organo-montmorillonite (OMMT) nanocomposite was modified by poly(ethylene-co-octene) (PEOc). PEOc-rich domains were well dispersed in the iPP matrix, with narrowly distributed size. OMMT layers were well dispersed, mainly intercalated and partially exfoliated. Compared with the case in the binary composites, many OMMT layers were preferential distributed inside and around the PEOc-rich domains in the ternary composite samples, which formed an enhanced OMMT filler network. The reason for the OMMT preferential distribution was considered to be dragged or wrapped by PEOc-rich domains during sample preparation and phase separation. (C) 2012 Elsevier Ltd. All rights reserved.