In the article the green synthesis of silver nanoparticles (AgNPs) by four extracts of Parachlorella kessleri the alga: solution A-a mixture of H2O and algae (also used as a stock solution), B-heat treated and centrifuged stock solution, C-heat treated stock solution, and D-centrifuged stock solution is performed. FTIR, UV-vis, TEM, light microscope and image analysis were used for the analysis of the solutions composition, synthesis process, AgNPs size and morphology, and changes caused by the solution type. The impact of extracts treatment on AgNPs synthesis rate, size, stability and amount was proved.