The parameters influencing the size of synthesized Ag nanoparticles are reported. The particles size decreased with increasing stabilizer: AgNO3 molar ratio, decreased with increasing amount of methanolic NaOH added until an optimum amount was reached, and decreased with small amount of methanolic HCl added but increased rapidly on further addition. The reducing activity of the reducing agent influenced the particle size significantly. In addition, increasing the concentration of water in the reducing agent increased the particles size nearly linearly. PVP is a better stabilizer than beta-CD to prevent aggregation of small particles. Microwave irradiation for 20 s at output power of 700 W produced smaller and more narrowly distributed Ag particles than conventional heating method. (C) 2004 Elsevier B.V. All rights reserved.