Nanofluids have drawn special attention during the last decades due to their various unique properties. It is revealed that the addition of nanotubes to the base materials can significantly change their properties. In the present work, the viscosity of water containing nanotube is calculated using the Molecular Dynamics Simulation for different volume fractions in the range between 0.557% and 3% at two temperatures (298K and 313K). The Green–Kubo equilibrium method is applied for calculating viscosity. The studied nanotube is an Armchair (6,6) single-walled carbon nanotube. The results show the potential of the Molecular Dynamics Simulation technique as a powerful tool in the prediction of nanofluid properties beside the experimental results. A new relationship for viscosity is offered for volume fractions of ϕ ≤ 3%, according to the obtained results.