TOM SAVU, BOGDAN ALEXANDRU JUGRAVU, DANIEL DUNEA ON THE DEVELOPMENT OF A PM2.5 MONITORING NETWORK FOR REAL-TIME MEASUREMENTS IN URBAN ENVIRONMENTS A monitoring network system was designed and developed to be deployed in two Romanian cities during the ROkidAIR project for measuring in real time the PM2.5 concentrations. The system comprises 8 stations that were built following the successful design and testing of a PM2.5 optical instrument prototype. The System’s Web services, the data acquisition from the monitoring stations, and the data sending to a GIS-integrated geoportal that includes a decision support system, were firstly evaluated for testing their effectiveness and for eventually defining necessary corrections. After describing the station’s structure and the Web services’ main functions, the paper presents data about the most important measured operating parameters of the stations, results from data processing, and conclusions for further developments. Preliminary information collected from a reference gravimetric sampler installed for data inter-comparison with the developed stations is also presented.