Large amounts of source separated organic (SSO) waste are generated in urban environments globally and there are limited management strategies to reduce their effect on the environment. Some indications exist that composting time can be reduced by using specialized organisms called ‘Effective microorganisms’ (EM). The current study is aimed at examining the role of EM toward reducing the time of SSO composting by accelerating maturity process. The experiment will be set up as a 3x4 factorial design with three levels of composting stages (initial, stabilization and combination of initial and stabilization stages) and four levels of inoculants (two commercial inoculants, an active compost and a control). Respirometry (CO₂ evolution) measurements were conducted to test maturity and the inoculated mature samples were tested for phytotoxicity by performing plant bioassay using cucumber plants.  Application of EM had an effect on the composting process and chemical characteristics of the composts.