The cocrystallization behavior of poly(n-octadecyl methacrylate) (POMA) and its blends with corresponding fatty acid (n-octadecanoic acid) (C-18) was explored by differential scanning calorimetry (DSC) and X-ray diffraction studies. The DSC curves for blended samples of POMA with C-18 show the characteristic melting endotherms that correspond to the melting of the cystallites. The existence of hexagonally packed crystalline lattice is confirmed from the X-ray diffraction studies. Thermal degradation of the polymer and its blend proceeds in a one-step reaction. (c) 2007 Wiley Periodicals, Inc.