The structural and dynamical properties of Ir(100) clean surface are investigated in the temperature range 100–1100K. We performed molecular dynamics (MD) simulations using the interaction potential energies obtained from the density-functional theory (DFT) and plane-wave pseudopotential (PWPP) method. The obtained contraction of the first interlayer distance, d 12 , decreases from −4.94% at 100K to −4.84% at 1100K. This decrease deviates by 11.8% at 100K to 13.6% at 1100K, from that at 0K (−5.6%). The expansion of the second interlayer distance, d 23 , however increases from 0.89% at 100K to 1% at 1100K, causing a deviation that ranges from −11% to 0% from that at 0K (1%). The deviation of the calculated surface vibrational frequencies and surface relaxations over the entire range of temperatures (100–1100K) is rather modest as a result of small anharmonic effects of the surface.