Thiocyanate (SCN-) is a metabolite of cyanide detoxification with equivalent toxicity. The SCNT, even in trace concentration affects the health adversely. Notwithstanding various methods have been used for SCN- analysis, a fast and simple electrochemical process has been hardly ever tried. Herein a novel material, carbon dots doped Fe3O4 embedded on g-C3N4 nanosheets (CDs/Fe3O4@g-C3N4) has been synthesized for the electrochemical detection of SCN- level in the saliva samples of smokers and nonsmokers of tobacco. The synthesized material was characterized by FT-IR, HR-TEM, TGA, UV-Vis and XRD analysis. The linearity range exhibited by this sensor is wide (0.001-0.900 mu M) and the detection limit is in picomolar. The proposed system can be very well applied for the construction of sensing devices for clinical diagnosis and environmental monitoring. (C) 2018 Elsevier Ltd. All rights reserved.