Microcapsules containing n-octadecane were synthesized using methacrylic acid (MAA), methyl methacrylate (MMA) and 1,4-butylene glycol diacrylate (BDDA) as shell. The surface morphology, thermal physical properties, thermal stabilities and diameter distributions of the microcapsules were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and particle size distribution analysis, respectively. The experimental results show that, the core material is well encapsulated in the presence of emulsifier-sodium salt of styrene-maleic anhydride co-polymer. The average diameter of the microcapsules is 18 mu m. The enthalpy of microencapsulated n-octadecane (MC18) with MAA-MMA co-polymeric shell is 155Jg(-1) which corresponds to 70 wt.% core content. The thermal resistant temperature of MC18 is 238 degrees C, which is affected by n-octadecane/monomers mass ratios and the content of cross-linking agent-BDDA. (C) 2009 Elsevier B.V. All rights reserved.