The Ozone meter for gases measures the ozone concentration according to standard DIN 19627 and the IOA (International Ozone Association) at a wavelength of 254nm. According to these standards, the extinction coefficient is 3024 l/mol cm. Therefore, the ozone measurement can be regarded as an absolute measurement requiring no calibration with ozone. The special measuring cell with a path-length of 100mm allows measuring ozone in ultra pure water in the ppb range. For inspecting the instrument, checking units on the basis of reference filters can easily be inserted. Operation is done intuitive using the intelligent control system SICON via touch screen technology and colour display. Values, graphs, alarm and status messages can be presented. An internal data logger allows recalling and displaying measured data from the last 32 days. A variety of analogue and digital interfaces allows smooth system integration and control.