Hydrogels were prepared from oxidized wood meals and chemical pulps by phosphorylation with phosphoric acid and urea. A transparent hydrogel, which was prepared from wood meals by oxidation with chlorite followed by phosphorylation, was capable of absorbing 115gH₂O/g sample. As oxidant, peracetic acid and ozone were also applicable to the pretreatment. Colored gels were obtained from phosphorylated kraft and sulfite pulps. The water absorbency of phosphorylated kraft pulp was 66gH₂O/g, while that of phosphorylated sulfite pulp was 29gH₂O/g. Wood meals phosphorylated without oxidation and the chemical pulps absorbed only several times each weight of water. These results indicate that the pretreatment with chlorite is the most effective for the hydrogelation.