Polypropylene (PP)/wood flour foamed composites were prepared by taking PP:wood flour in the ratios of 100 : 0, 90 : 10, 80 : 20, 70 : 30, and 60 : 40 (w/w), with and without compatibilizers like maleic anhydridetreated wood flour and maleic anhydride-grafted PP (PPgMA). The foamed composite samples were employed for water swelling at 27 degrees C, 70 degrees, and in steam. The absorption of water increased with increase in filler contents for all three-temperature conditions. The maleic anhydride-treated wood flour and PPgMA showed reduction in water swelling, and the best one was in case of the PPgMA-foamed composites for respective conditions. Diffusion, sorption, and permeation coefficients were determined to study the absorption kinetics. FTIR spectra were also recorded for 30 wt % of filler loading for all the composites, which showed the effect of compatibilizers on reduction in water absorption in foamed PP/wood flour composites. (c) 2006 Wiley Periodicals, Inc.