© 2018 Universidad Autonoma de Tlaxcala. All rights reserved. Recently the demand in the development of eco-friendly nanoparticles as alternative to chemical and physical methods has been increasing so the aim of this study was to evaluate the effect of silver nitrate concentration and extracellular filtrate (EF) produced by a filamentous fungus isolated from a spent catalyst and coded e identified as Penicillium purpurogenum CATMC-AH-1 on Silver nanoparticles (AgNPs) production. The filamentous fungus was growth in two culture media named Sucrose and Czapeck media to produce biomass and its was put in contact with water to get two different extracellular filtrates called EFS (extracellular filtrate sucrose) and EFC (extracellular filtrate Czapeck), the EF has the molecules involved to synthesis and stabilization of AgNPs. Three concentrations of AgNO3 1, 1.5 and 2 mM and both extracellular filtrates were used to produce AgNPs. The AgNPs produced were monitored by UV-visible absorption spectra from 200 to 800 nm while their morphology and size were identified by Transmission Electron Microscopy (TEM) and software analysis SPIP 2.6.0. Results showed that both extracellular filtrates had the ability to produce AgNPs with the three concentrations of AgNO3 used. TEM analysis showed AgNPs with spherical morphology in all systems. The AgNPs synthesized in EFS with the three AgNO3 concentrations showed average sizes of 8.9, 8.4 and 6.7 nm respectively. From EFC, the average sizes of AgNPs were of 14.9, 11.5 and 10.1 nm respectively. In summary, in EFS smallest sizes and diameter dispersion of AgNPs were obtained, comparing to EFC and the spherical shape was similar in both filtrates. The AgNO3 concentration had a positive effect when the EFC filtrate was used since a direct correlation was observed between the concentrations of silver nitrate and increase the absorption band around 420 nm as result of surface plasmon resonance of AgNPs produced. The AgNPs biosynthesized from both EF (EFS and EFC) could be used as antimicrobial agent by their small size. Parameter as silver nitrate concentrations and culture media are important because could be affect the size and concentrations of AgNPs biosynthesized.