In this study, the effect of carbon nanotube (CNT) on the dielectric parameters of (11-(4-cyanobiphenyl-4'-oxy)undecan-1-ol) (coded as) LC11 has been investigated by dielectric spectroscopy measurements. According to analysis of ac dielectric parameters' analysis, while relaxation frequency increases with CNT doping, the magnitude of energy loss decreases. In this respect, CNT doped LC11 material which can be utilized in the wide working frequency interval with low energy requirements, has a great potential for technological applications. On the other hand, CNT adding changes the relaxation type from nearly Debye to non-Debye type. In addition to these remarkable modifications on the dielectric parameters, it has been determined that CNT doping extends the frequency interval where the liquid crystal (LC) system shows negative dielectric anisotropy (NDA). In other words, observation of the NDA at the higher frequency region relative to LC11 means that the molecular alignment can be controlled by CNT. Hence, tuning the alignment of the LC11 molecules by CNT doping may lead its utility for various LC device applications. (C) 2015 Elsevier Ltd. All rights reserved.