A polypropylene/high-density polyethylene blend containing 70 wt % polypropylene was prepared and compatibilized via the addition of maleic anhydride grafted polypropylene and polyethylene. The functionalized polymer chains were coupled with two types of coupling agents. Dodecane diamine formed covalent bonds with the maleic anhydride, whereas two metallic salts, zinc acetate and sodium hydrogenocarbonate, formed ionic interactions with the carboxylic functions produced by the hydration of the anhydride cycle. The coupling of the grafted polyolefin chains was successfully realized by a single operation in a twin-screw extruder. The coupling agents were efficient in improving the elongation at break and impact properties of the studied blends. (C) 2004 Wiley Periodicals, Inc.