In this study, N-(Rhodamine-6G)lactam-N'-acryloyl-ethylenediamine (RH6GAC) as co-monomer was synthesized in two steps and characterized by FT-IR, H-1, C-13 NMR and mass spectrometry. Metal ion (Na+, K+, Ca2+, Fe2+, Fe3+,Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, Hg2+, Mn2+, Ba2+, Mg2+) selectivity of RH6GAC was investigated by UV-Vis and fluorescence spectrophotometry. Then, Fe3+ ion selective and reusable naked-eye calorimetric copolymeric sensor hydrogels were synthesized using 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) as the primary monomer and N-(Rhodamine-6G)lactam-N'-acryloyl-ethylenediamine as comonomer by free radical polymerization. The sensor hydrogel was characterized by FT-IR and swelling properties. (C) 2013 Elsevier B.V. All rights reserved.