Phase transitions and molecular orientation in nematic liquid crystals (E7, E8, E63 and ZLI-1132) doped with blue dye (disperse blue 1, 3, 14 or 134) and blue 14 + red dye (disperse red 1, 60 or methyl red) mixtures were studied. At the second stage, effects of single-walled carbon nanotubes (SWCNTs) added to them were determined. When blue-red dye mixtures were doped into the liquid crystals, an increase in order parameter was observed compared to those of single dyes and a value of 0.70 was attained. The addition of carbon nanotubes resulted in very higher values of order parameter (Smax = 0.79). To determine the threshold value of order parameter for saturation, the experiments were repeated in various DC voltages. The threshold voltage was significantly reduced with addition of CNTs. With addition of dopants, an appreciable change in textures was not observed. Shifts in phase transition temperatures were in limitations required. Copyright © Taylor & Francis Group, LLC.