This work describes a simple wet chemical synthesis of iron oxide (Fe3O4) nanoparticles (NPs) capped with terephthalic acid (TA) and their application for the individual detection of Hg(II), Pb(II) and Cd(II) ions as well as simultaneous and selective detection of Hg(II), Pb(II) and Cd(II) ions by electrochemical approach. Terephthalic acid capped Fe3O4 NPs were first characterized by cyclic voltammetry (CV) using redox couples Fe(CN)63 −/4 −, thereafter square wave anodic stripping voltammetry (SWASV) was utilized for the detection of Hg(II), Pb(II) and Cd(II) ions. Optimization of experimental parameters such as deposition time, deposition potential and pH value of the electrolyte towards electrochemical detection of target heavy metal ions was also carried out in SWASV method. Under optimized experimental conditions limit of detection (LOD) values for individual analysis of Hg(II), Pb(II) and Cd(II) ions were found to be 0.1, 0.05 μM and 0.01 μM respectively, whereas the LOD values for the simultaneous analysis of Hg(II), Pb(II) and Cd(II) ions were found to be 0.3 μM, 0.04 μM and 0.2 μM respectively. © 2017 Elsevier B.V.