Polyepoxysuccinic acid (PESA) and polyaspartic acid (PASP) have proven to be green corrosion scale inhibitors given their non-nitrogenous, non-phosphorus, and biodegradable features. This study aims to provide better guidance on PESA and PASP applications in cooling water system and identify the feasibility of their synergistic effect on scaling inhibition. The anti-scaling performance of PESA and PASP was compared using the static and rapid controlled precipitation methods. Results showed that in CaCO3 and SrSO4 control, PESA performance exceeded that of PASP. In contrast, PASP performed better than PESA in terms of CaSO4 center dot 2H(2)O and BaSO4 scale inhibition. The anti-scaling performance of PESA was superior to that of PASP for CaCO3. and the concentration of PESA needed to attain the same efficiency was lower than that of PASP. Increasing Ca2+ concentration or temperature reduces the inhibition effects of PESA or PASP. SEM and XRD analyses demonstrated modifications in crystalline morphology in the presence of PASP and PESA. (C) 2012 Elsevier B.V. All rights reserved.