Maleic anhydride modified polyethylene (PEgMA) coupling reactions were realized using a dioxazoline coupling agent, (1,3-phenylene)-bis(2-oxazoline), in an internal mixer. In preliminary studies and in model reactions, it was shown that ai-diydride/oxazoline reactions were very slow or nonexistent compared to acid/oxazoline reactions. The main observed coupling is due to acids resulting from anhydride hydration. In a second part, the coupling reactions were preceded by an anhydride hydration realized by direct injection of different water quantities. In these cases, the couplings were more efficient than when PEgMA were directly used. At high temperature some of the formed succinic acids were dehydrated, leading to the initial succinic anhydrides. The study of the effect of the molar ratio of oxazoline/anhydride on the PEgMA coupling showed that the maximum apparent coupling was obtained when the ratio was 4. (c) 2005 Wiley Periodicals, Inc.