Flexible transparent conducting films with sodium dodecyl sulfate-dispersed singlewalled carbon nanotubes (SWCNTs) were prepared by a spray method and were further immersed in various acids. The film conductivity was enhanced by a factor of similar to 4 with a negligible change in the transmittance in the visible range. This enhancement was attributed to the removal of remaining SDS and the subsequent densified film formation to improve the cross-junction resistance between SWCNT networks and enhanced metallicity of SWCNTs.