A novel, biodegradable and environmentally benign magnetic porous chitosan-thienyl imine palladium(II) complex, MPCS-TI/Pd, was prepared and characterized by FT-IR, SEM, TEM, EDX, XRD, BET, VSM and TG-DTA analysis. This complex, with high surface areas and low catalyst loading, was found to be a highly active and robust heterogeneous catalyst for the Mizoroki-Heck reactions of aryl bromides and chlorides with various terminal olefins in aqueous media in good to excellent yields. The catalyst was easily separated by an external magnet and the recovered catalyst was reused in seven cycles without significant loss of catalytic activity.