Vortex-Induced Vibration (VIV) is a major concern in design of slender structures exposed to the wind flow, such as high-rise buildings and bridges, or water currents, such as offshore structures, marine risers, mooring elements and free spanning pipelines. Many researchers have investigated VIV of circular and rectangular crosssections. However, flow characteristics and VIV of hexagonal cylinders have received limited attention so far. Vortex-induced vibration of infinitely long hexagonal cylinders with corner and face orientations are investigated herein using two-dimensional Computational Fluid Dynamics (CFD). The numerical model is based on the solution of two-dimensional Reynolds-Averaged Navier–Stokes (RANS) equations in ANSYS Fluent. The RANS equations are solved in a moving mesh system using the Arbitrary- Lagrangian–Eulerian (ALE) approach, which allows the cylinder to move as a rigid body in the cross-flow direction. Turbulence is incorporated using the Shear Stress Transport (𝑆𝑆𝑇) 𝑘– 𝜔 model. The numerical model and results are validated against published experimental and numerical results on VIV of a circular cylinder for a Reynolds number (𝑅𝑒) of 1000. Using the validated model, VIV of hexagonal cylinders with corner and face oriented configurations are studied at reduced velocities (𝑉𝑟) between 2 and 12. In all models the non-dimensional mass ratio (𝑚∗) of 2, and 𝑅𝑒 of 1000 are adopted. Results are presented in the form of drag and lift forces, vortex shedding patterns, flow velocities, pressure distributions around the cylinders, frequency of vibrations, Strouhal numbers and amplitude of vibrations. Results show that, the cross-flow amplitudes of vibration of both corner and face-oriented hexagonal cylinders are much lower than that of a circular cylinder of the same diameter. The vortex shedding frequencies of the hexagonal cylinders are smaller than the circular cylinder.