Silver nanoparticles are well known for their antimicrobial properties and have been widely used in medical and industrial applications to prevent the growth of microorganisms. The effectiveness of silver nanoparticles (AgNPs) as an antimicrobial material is influenced by their shape and size; the smaller the size, the more active the AgNPs. To prevent aggregation, the nanoparticles can be maintained by stabilizing agents. This study aims to synthesize silver nanoparticles in situ using cellulose paper and to evaluate their antimicrobial activity. For reduction of Ag+ ions were used propane-1,2-diol. The reduction was carried out at 60, 80, and 100o C to accelerate the reaction. The formation of silver nanoparticles can be seen from the change in paper color from white to yellow or brown. This result is confirmed by the occurrence of the absorption peak in the UV-Vis spectrum between 300-500 nm. The TEM image shows the size distribution of silver nanoparticles affected by their reduction temperature. Antimicrobial tests provide a clear zone from the bottom of the paper to the edge. The reaction temperature at 60o C showed the best antimicrobial activity with AgNPs averaging at 6 nm. This method can be applied to antimicrobial paper preparation with controlled size and distribution.