Molecular dynamics simulations of one HCl molecule in liquid Ar at three different thermodynamic states have been carried out. The dynamic properties of both the solute molecule and solvent atoms are discussed. Results for Ar in the first solvation shell of HCl are compared with those for atoms in the bulk. The study includes radial distribution functions, residence times, velocity autocorrelation functions, spectral densities, self - diffusion coefficients, reorientational time correlation functions and infrared spectra.