In this study, hydrophilic monomers were photografted onto the PP plates at different monomer concentrations and temperatures, and grafted PP plates were bonded with enzymatically modified chitosan solutions. Their adhesive strength properties were discussed in relation to the grafting conditions and hydrophilic properties such as wettability and water-absorptivity. In addition, the location of failure was investigated by X-ray photoelectron spectroscopy analysis of failed surfaces. Wettability of the grafted PP plates except for the PP grafted with acrylic acid (PP-g-PAA) plates remained constant above the grafted amounts at which the PP surfaces were fully covered with grafted polymer chains. On the other hand, wettability of the PP-g-PAA plates passed through the maximum value and then gradually decreased with the grafted amount probably because of the aggregation of grafted PAA chains. Water-absorptivity of the grafted layers formed at lower monomer concentrations or temperatures sharply increased at lower grafted amounts. The adhesive strength increased with an increase in the grafted amount and substrate breaking was observed for PP-g-PAA plates because enzymatically modified chitosan solutions were successfully penetrated in the grafted layers and quinone derivatives reacted with carboxy groups of grafted PAA chains. Failure occurred in the layers composed of grafted PAA chains and components containing in enzymatically modified chitosan solutions and the location was shifted to the inside of grafted layer, as the grafted amount increased. (C) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1369-1376, 2013