Abstract: Capability of different microorganisms to produce nanoparticles of silver (NPAg) at different pH levels was studied. It was established that pH of the reaction medium considerably affects form and size of produced nanoparticles. The fact of NPAg formation produced by the different microorganisms was studied by UV-spectroscopy and AFmicroscopy methods.It was determined that in the selected conditions of the synthesis both clusters and nanoparticles of silver are produced ranging in size from 20 to 300 nm and form absorption bands at max275 nm and 420 nm, respectively. It was revealed that changeof pH level of the reaction system may result in regulation of the size and form of the nanoparticles.