Physical, chemical and tribological properties of the MoSex and MoSexCy coatings for micromechanical applications grown by pulsed laser deposition in vacuum and in a rarefied inert gas (argon) atmosphere are studied. In a number of experiments a disk-shaped screen was used that is placed on the path of the expansion of laser plume in order to trap the droplet fraction. Upon deposition in a gas at a pressure of ~2 Pa, stoichiometric MoSe2 coatings with improved antifriction properties as compared vacuum-deposited MoSex (x<2) coatings form. However, a too strong increase in the argon pressure (to ~10 Pa) degrades the tribological properties of the coating. Deposition in vacuum or argon at a pressure of 2 Pa leads to formation of rather smooth coatings with a dense amorphous structure containing molybdenum nanoinclusions. Numerical experiments based on the combination of two computer models that describe physical processes on the atomic level using Direct Simulation Monte Carlo and Kinetic Monte Carlo methods are performed to reveal the factors that affect the thickness, chemical composition, and structure of the MoSx-based coatings. Deposition to a negatively biased substrate is shown to substantially increase the coating density and to smooth the surface relief.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.