AbstractPaper/polyacrylic acid (PAA) composites were prepared using a micro-crystalline cellulose (MCC)-reinforced PAA hydrogel. The MCC-reinforced PAA hydrogel was prepared by in-situ UV light-induced polymerization of acrylic acid in the presence of MCC. The experimental results showed that the presence of MCC improved the water absorption capacity of the resulting PAA hydrogel. The addition of 1 wt% MCC (based on the dry weight of acrylic acid) in the hydrogel matrix resulted in an increase in the water absorption capacity of the PAA hydrogel by 122 g water/g hydrogel (i.e., from 427 to 549 g/g). Paper/PAA composites were then made by surface loading of the MCC-reinforced PAA hydrogel fine particles. Using 2 g of MCC-reinforced PAA hydrogel particles per square meter of paper, the water absorbance of the paper/PAA composites reached 1096 g/m2. Potential applications of these paper/PAA composites are also discussed in this work.