Composting is one of the ways of natural neutralization and management of different types of bio-wastes. In recent years much attention has been paid to researches on composting of variety of materials, including those containing sewage sludge. Due to the perceived need to automate and improve the implementation of researches on composting processes with the use of the bioreactor located in the Ecotechnology Laboratory of Poznań University of Life Sciences, the objective of the presented study was to develop a hardware-software system for monitoring the temperature of composted material placed in the chambers of the bioreactor. This system is based on the Arduino platform. The system allows to monitor the temperature in 6 bioreactor’s chambers and the ambient temperature, using for this purpose 13 digital temperature sensors Maxim DS18B20. The paper includes exemplary results of changes of composted material's temperature obtained using the system, which were the basis of its validation. It was found that this system works properly and meets the assumptions, thus it may help to automate researches on composting.