SILVER nanoparticles (AgNPs) with tailored characteristics are prepared using carboxymethyl chitosan (CMCs) which plays a dual role ; as a reducing agent for conversion of Ag+ to Ago and as a stabilizing agent to prevent aggregation of Ago and / or its clusters. The preparation involves a thorough investigation into factors affecting formation of AgNPs characteristics and dependence of them on these factors. Factors studied encompass concentrations of silver nitrate and CMCs as well as pH, time and temperature of the synthesizing medium. Sophisticated tools such as FT-IR, UV-vis spectral analyses and TEM reveal major characteristics of AgNPs formed as well as size, distribution and shape of AgNPs. According to current work, the most appropriate condition of converting silver ions into AgNPs are 0.25% solution of CMCs and 6ml of 0.1N AgNO3 (0.102 g / 100 ml) and carrying out the reaction at 70 oC for 45 min at pH 11.