High-performance blend of polypropylene (PP) and polycarbonate (PC) has not been explored. The difficulty is caused by the big differences in melt viscosity (PP: low viscosity vs. PC: high viscosity) and polarity (PP: nonpolar vs. PC: polar). We put forth a new approach using a reactive plasticizer which is preferentially soluble with PC and polymerizable by organic peroxide. As the plasticizer, diallyl phthalate and triallyl cyanurate (TAC) were used. By reactive extrusion of PP/PC/plasticizer/dicumyl peroxide (e.g., 80/14/6/0.12 wt. ratio), reaction-induced phase decomposition took place in the dispersed PC particles to develop a regularly phase-separated nanostructure and the graft copolymer of PP and polymerized plasticizer was in situ generated at the interface. The extruded blend showed an excellent ductile behavior with about 500%-elongation at break. TAC was very effective to elevate the heat resistance. Then, a super-ductile PP/PC blend with high heat resistance was successfully developed. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013