In the present study, the aerobic compostability of municipal solid wastes collected from the Composting and Recycling Plant of Istanbul Metropolitan Municipality (IMM) was investigated. A laboratory scale consisting of a cylindrical reactor with air pump and temperature sensor was used in the experimental setup. Parameters affecting the composting process such as pH, temperature, moisture content, total kjeldahl nitrogen (TKN), volatile solids were followed during 56 days in the reactor. Compost self-heating was measured by performing the Dewar test to determine the stability of the compost. At the end of the study, Salmonella test was used for the detection of pathogenic microorganisms. Also, a phytotoxicity test was performed using the cress seeds (Lepidium sativum). The study results showed that Istanbul municipal solid wastes can be used as composting materials, and the compost produced has been attested to be suitable for agricultural activities.