Measurement of concentrations of gas components in the air is important in various fields of human activity: environmental protection, biochemistry, medicine, agriculture, food technology, sports, etc. In this paper is presented the possibility of a radio frequency identification (RFID) type sensor capable of functioning in wireless sensor networks (WSN) and aimed for measuring the concentrations of gas components in the air. The sensor consists of an electrochemical cell for sensing an air gas component, a potentiostat type measuring circuit, a coordinating microcontroller and an RFID tag. Practical implementation was based on an O2-A2 electrochemical cell, the integrated LMP91000 potentiostat, the MSPG2233IPW20 microcontroller and the Andy100 RFID transponder. With this system, measurements have been made in order to determine the degree of oxygen in the air. By using other electrochemical cells the concentrations of other gas components in the air or fluids in general can be determined.