[en] Nano powders are powders with particle size less than 100 nanometer. The applications of nano powders are in the production and processing of nano composites, microelectronic, industrial catalysts, coating sintering at low temperature, lubricants, propellants, purification of aqiuos solutions, biomaterials and filtration. In this work, a reactor for production of nano powder using gas phase condensation method was designed and manufactured. By changing the production parameters such as chamber temperature and pressure, evaporation rate, precursor and evaporation time, Silver powders were produced. The characteristics of the produced powders were studied using EDX, SEM and TEM techniques. The results showed that powders with particle size between 2-60 nm can be produced. These powders had spherical shape but they were very aggregated. The particle size increases with chamber pressure and temperature