Polyacrylonitrile (PAN) particles synthesized by dispersion/emulsion polymerization of acrylonitrile monomer were cross-linked with hydrazine in order to prevent its dissolution in water when they were subjected to hydrolysis. Hydrazine-crosslinked PAN (cPAN) particles were hydrolyzed with NaOH solution in order to impart them with high hydrophilicity. The effects of the cross-linking degree, i.e., the hydrazine concentration during the cross-linking of PAN, NaOH concentration on the hydrolysis behavior of cPAN particles and their particle shapes were analyzed. Results revealed that cross-linking of PAN with 5% hydrazine solution at $110^{circ}C$ for 3 hours and hydrolysis of cPAN with 5% NaOH solution at $80^{circ}C$ for 3 hours is suitable for the preparation of highly hydrophilic and water-insoluble PAN particles. Then, hydrophilicity and the heat release property of the hydrolyzed, cross-linked PAN (h-cPAN) particles were examined. The h-cPAN particles exhibited a temperature rise of up to $11^{circ}C$ by water absorption and a moisture regain of up to 23% at $20^{circ}C$ and 65% RH, depending on the hydrazine cross-linking and NaOH hydrolysis conditions. Cotton fabrics were treated with h-cPAN dispersion solutions of different concentrations by a normal pad-dry process. The temperature changes of the treated fabrics by water absorption were measured. The h-cPAN treated fabrics showed higher temperature rise by moisture absorption compared to untreated one. It indicates that the particles can be used as a potential moisture-absorbing heat release finishing agent for textiles.