To stabilize phase change material, disodium hydrogen phosphate dodecahydrates (Na2HPO4 center dot 12H2O), a novel gelling method by polymerizing sodium alginate grafted sodium acrylate in its molten salt was investigated. The optimum synthesis conditions to obtain product with stable heat storage performance were 2.8% (w/w) sodium acrylate, 0.3-0.4% (w/w) sodium alginate, 0.1-0.19% (w/w) NAP-methylenebisacrylamide and 0.06% (w/w) K2S2O8 and Na2SO3, at 50 degrees C. Na2HPO4 center dot 12H(2)O was dispersed in the as-synthesized gel network as tiny crystals less than 0.1 mm. Melting points were in the range 35.4 +/- 2 degrees C. Short-term thermal cycling proves the effectiveness of the novel gelling method for eliminating phase separation in the gelled salt. (C) 2007 Published by Elsevier B.V.