The sodium acetate trihydrate is commonly used as energy storage phase change material in heating pads for body or hand warmer in cold climates. The undercooled melt of sodium acetate trihydrate kept at room temperature results in an exothermic reaction when solidification seed is nucleated. In presentwork, modeling of denritic growth in an undercooled solution of sodium acetate trihydrate has been carried out. The enthalpy method has been used to compute solid-liquid interface growing in undercooled melt. The interface temperature, concentration and grain growth have been modeled considering curvatureeffect and solutal undercooling. A 2-D computational grid of square control volumes has been used and discreatized governing equations were solved explicitly. The crystal anisotropy was imposed explicitly. The results are validated using experimental data. © The Authors, published by EDP Sciences, 2019.