In this work, we discuss the structural and transport properties of iodine intercalated amorphous conducting carbon (a-C:I) films prepared by vapor phase pyrolysis of maleic anhydride and iodine. X-ray photoelectron spectroscopy studies reveal the presence of iodine in the a-C:I samples. Microhardness measurements of the films show a decrease in the value of the hardness with an increase in iodine concentration. Iodine incorporation accounts for a change in electrical conductivity of the a-C samples. Magnetoresistance measurements performed on a-C:I samples show a decrease in the value of magnetoresistance. The thermal stability of a-C:l samples has been studied by thermogravimetric analysis, which is found to depend on the host structure and amount of intercalated iodine. (C) 2004 Elsevier B.V. All rights reserved.