A simple, low-cost technique for particles velocity measurement in the gas deposition method (CDM) is reported. The accuracy of the technique is determined only by the precision of measurements of geometrical sizes of deposited pattern. Self-selection of the particles with parameters acceptable for deposition occurs. Under typical deposition conditions the velocities about 200 m/s for ceramic particles and up to 650 m/s for metal ones were detected. The proposed technique allows in situ monitoring during deposition both by GDM and by other deposition methods.