In this paper, a semi-classical one-dimensional (1D) electron fluid model is built that is based on a classical two-dimensional electron fluid theory taking into account electron–electron repulsive forces, which are significant in 1D system. We have used 1D fluid model to characterize the carbon nanotube (CNT) as interconnects, built a transmission line model and studied S-parameters and group delays. We have also compared S-parameters and group delays of CNT interconnects with the corresponding parameters of Cu interconnects. The results show that the CNT interconnects exhibit superior performance over the Cu interconnects. The results also suggest using CNT as interconnects for radio frequency (RF)/microwave applications. Copyright © 2009 John Wiley & Sons, Ltd.