Electrical and morphological characteristics of polypyrrole (PPy) films electro-deposited in four different aqueous electrolyte solutions including p-toluenesulfonate, dodecylsulfate, poly (styrenesulfonate), and perchlorate have been investigated using current-sensing atomic force microscopy. Experimental parameters including the electrolyte, applied current density, and deposition time were shown to affect the morphologies and current images of PPy films thus prepared. The PPy films were galvanostatically prepared under the identical conditions except for different electrolytes; the globular-shaped topographic structures with the unusually large sizes were obtained in dodecylsulfate. The p-toluenesuffonate doped PPy film showed the highest average conductivity whereas the perchlorate doped one showed the lowest of all the films prepared. (c) 2005 Elsevier Ltd. All rights reserved.