Silver nanoparticles (AgNPs) are widely developed because of their unique optical, electrical, and photochemical properties. In the nanoparticle synthesis reaction, optimum conditions are needed to obtain desired nanoparticles with a certain shape and size. In this study, the synthesis reaction of nanoparticles was carried out using the polyol method with a modification, i.e by changing the temperature reaction to below than the normal temperature method in a polyol synthesis (140°C to 100°C). In this study, the synthesis of AgNPs was carried out using ethylene glycol (EG) as a reaction medium and also reducing agent poly (vinylpyrrolidone) (PVP, Mw: 55,000) as a capping agent, and silver nitrate (AgNO3) as a precursor with the addition of hydrochloric acid (HCl) as an additive. Here the concentration of AgNO3 dan HCl was varied to control either size or shape of AgNPs. The resulted AgNPs were characterized using UV-vis spectrophotometer, Transmission Electron Microscopy (TEM), and X-Ray Diffraction (XRD). The UV-vis spectra data show that the concentration of HCl decreased the reduction rate of Ag+ ions to Ag atoms which were due to the etching process conducted by the Cl-/O2 pair in the solution. The XRD data show the formation of AgNPs together with the presence of AgCl crystal structure. The TEM results indicate the formation of AgNPs with varying sizes depending on the concentration of HCl and AgNO3 precursor, while that for shape remains unchanged.