A Nafion modified platinum electrode-on-chip for the electrochemical detection of iron in 0.1 M HCl has been demonstrated. The platinum electrode was patterned on a silicon substrate by a combination of microfabrication processes followed by spin coating deposition of a Nafion layer. The quality of the thin-film chip structure and the low surface roughness of the Nafion coated platinum nano-grains were observed by FE-SEM and AFM techniques. These features contributed to a significant improvement in the electrode performance in terms of sensitivity as it can offer: (i) a low and stable baseline current,- (ii) a high faradic current with respect to the reduction of Fe3+. Under optimum conditions,- the electrode operates in the range of 1 ppb to 250 ppb with a detection limit of 0.31 ppb. It also exhibits an excellent reproducibility with a relative standard deviation (RSD) of 6.11% for 20 repeated measurements. The electrode has been successfully applicable for detecting iron concentrations in natural water samples. © 2020 Elsevier B.V.