Transparent conducting films (TCFs) are made of different single-walled (SW) or multi-walled (MW) carbon nanotubes (CNTs), some of them previously modified by chemical or physical processes. The TCFs are prepared by spray-coating of CNT surfactant dispersions over glass substrates. Among pristine CNTs, laser-grown SWCNTs lead to the lowest resistivity, even though good results can be achieved with other selected SW or MWCNTs. Ultracentrifugation of the SWCNT dispersions can be utilized for improving the characteristic SWCNT spectroscopic signals. Controlled oxidation, acid treatment, and covalent functionalization with aromatic organic groups can be applied to CNT solid powders without substantially increasing the resulting TCF resistivity. The oxidative transformation of arc-discharge MWCNTs into graphene nanoribbons relatively improves their TCF performance. The positive effects of TCF washing with water or oxidant acids are quantified for various SWCNT types. Red and green inks, enriched in metallic or semiconducting SWCNTs, are obtained by the gel-chromatographic method, all the fractions being useful for the preparation of TCFs. Thus, it is shown that different physical and chemical processes can be performed on CNTs before or after their deposition, demonstrating a great chemical versatility for CNT-TCFs. (C) 2015 Elsevier Ltd. All rights reserved.