Thecurrentapproachdiscusseda synthesis andcharacterizationofpolyaniline(PANI) andtwomodifedloading of 5, 10% Tl2O3-SiO2/ PANI,inwhich Tl2O3-SiO2 nanoparticles (NPs) were modifed with PANI forming na- nocomposites.The composite formation and structure were confrmed by X-ray difraction (XRD),UV–vis ab- sorptionspectra (UV–vis), Fourier transforminfrared spectroscopy (FTIR),scanning electronmicroscopy (SEM) withenergy dispersive X-ray spectroscopy (EDX), Highresolutiontransmissionelectronmicroscopy (HR-TEM), and dynamic light scattering (DLS) technique. The prepared polymer (PANI) and its nanocomposites (Tl 2O 3- SiO2/PANI) were examinedas a corrosionprotectivelayer for carbonsteelin 2.0NHClatdiferenttemperature (30–60°C) by diferent electrochemical methods including potentiodynamic polarization (PDP) and electro- chemical impedance spectroscopy (EIS) measurements. PANI inhibited the corrosion of carbonsteel, yielding maximumprotectioncapacity of89%,whichwerefurtherincreasedto96%by the modifcationwithTl 2O 3-SiO 2 nanocomposites.TheSEM/EDXinvestigations confrmedthepresence ofTl 2O 3-SiO 2/PANInanocompositesflm covering the metalsurface.