A systematic study of the dielectric response of dichloromethane over a broad frequency range (8: 5 <= nu/GHz <= 1000; <= 4.3 THz at 25 degrees C) at temperatures from 5 to 35 degrees C is reported. The spectra are best described by a superposition of three contributions. The dominating loss peak at similar to 70 GHz, fitted by a modified Debye equation accounting for inertial rise, represents the rotational diffusion of molecular dipoles. Additionally, two libration modes contribute, which are described by damped harmonic oscillators of resonance frequencies similar to 0.9 THz and similar to 2.1 THz. While the latter modes reflect the anisotropy of the dichloromethane molecule, the diffusive reorientation at long times appears to be rather isotropic. (C) 2009 Elsevier B.V. All rights reserved.