Plasma polymer films were deposited from an argon and acetylene mixture by plasma enhanced chemical vapor deposition in pulsed r.f. discharges. The discharge on-time varied from 50 to 150 ms and the off-time was kept constant at 1900 ms. The kinetics of the film growth was studied by in situ reflectance measurements. The films were further investigated ex situ by spectroscopic ellipsometry, atomic force microscopy, scanning and transmission electron microscopes. Damages in the films caused by residual stress were investigated with an optical microscope. The hydrogen content and film densities were measured by nuclear resonance reaction analyses. Some film properties namely the residual stress, deposition rate, optical properties and surface roughness were significantly influenced by the duration of the discharge pulses. We found refractive indices of the films in the visible in the range 1.60-1.73. The hydrogen-to-carbon ratio in the films and the film density were approximately 3:2 and 0.6 g/cm(3), respectively.