High-impact polypropylene (HIPP) is a commercially important polymer alloy with complex morphological structure. In this contribution, two commercial HIPPs have been investigated in detail by atomic force microscopy-infrared in conjunction with local thermal analysis to determine the composition and structure of the nanodomains. Both alloys contain numerous core-shell rubber particles dispersed in polypropylene matrix. In HIPP-1, the rigid cores of the particles are rich in polypropylene, which is highly crystalline, whereas for HIPP-2, the major component of the rigid cores is polyethylene with a high degree of crystallinity. The formation of these very different structures and compositions in the core and rubber domains may be attributed to different chain structures and compositions of the copolymers in the alloys produced by different catalysts. (C) 2018 Elsevier Ltd. All rights reserved.