Crystallization behavior and polymorphism of CaCO3 were studied at different temperatures (from 60 to 240 degrees C) under the influence of ethylenediaminetetraacetic acid (EDTA). The samples were characterized using powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM) and field emission scanning electron microscopy (FESEM). In the absence of EDTA, a calcite-aragonite binary mixture was resulted between 60 and 170 degrees C above which calcite alone was formed. The presence of EDTA significantly influenced the crystallization behavior and composition of different polymorphs of CaCO3 varied with temperature. Formation of a binary calcite-aragonite mixture at 60 degrees C, ternary calcite-vaterite-aragonite mixture at 100 degrees C, a binary aragonite-vaterite mixture at 130 degrees C, a binary calcite-aragonite mixture at 170 degrees C, purely aragonite at 200 degrees C and vaterite with very little aragonite at 230 degrees C confirmed that temperature affects the crystallization process in the presence of EDTA. Rhomboidal calcite, needle/rod like aragonite and flower like vaterite were obtained under different conditions. At 230 degrees C. a unique flower like morphology was observed for vaterite. The efficacy of EDTA on CaCO3 scale inhibition between 60 and 230 degrees C is discussed. (C) 2012 Elsevier B.V. All rights reserved.