RFieldbus is a modified kind of PROFtBUS fieldbus system featuring the extended wireless physical layer and the IP transmission capability This paper describes the results of a number of tests which were made to assess the RFieldbus behaviour. PROFIBUS-DP cyclic data exchange time, TCP/IP traffic throughput as well as error performance of the transmission mechanisms were evaluated in laboratory as welt as in industrial environments. The results show that in the industrial environment, an RFieldbus system can fully meet the real-time requirements even accompanied with the TCP/IP traffic.