Early stages of Sn-doped In 2O 3 (ITO) film deposition on room temperature (RT) acrylic-coated polycarbonate (PC) substrates using dc magnetron sputtering were investigated, by comparing them with those on RT soda-lime glasses. The microstructure and electrical properties of the films were analyzed as they grew from 1 to 330 nm. The ITO/glass had conductivity when the thickness was larger than 4 nm, whereas the ITO/PC had conductivity at a thickness larger than 14 nm, and became constant at about 21 nm. According to a result obtained by AFM, average roughness ( R a) of the ITO/glass surface showed remarkable change with increasing thickness reflecting initial nucleation, coalescence and continuous film growth processes, i.e. Volmer–Weber-type initial growth. Whereas, in the case of ITO/PC, R a was almost constant, except for the peak caused by substrate damage at a thickness smaller than 4 nm.