Seawater from the Arabian Gulf was heated under conditions simulating those of thermal desalination processes and the change in the amount of aquated Ca2+ followed over time using Inductively Coupled Plasma/Optical Emission Spectroscopy. This was done in the absence of any scale inhibitor, and in the presence of scale inhibitors: three commercial polycarboxylate products commonly employed in thermal desalination plants and four novel poly(acrylic acid) inhibitors of differing molar masses and end-group functionality. At times >2 min, the novel poly(acrylic acid) scale inhibitors of low (similar to 2000) molar mass and moderate (hexyl isobutyrate or cyclohexyl isobutyrate) end-group hydrophobicity were more effective in maintaining the aquated Ca2+ level than any commercial product. (C) 2015 Elsevier B.V. All rights reserved.