W e developed ana tested a LangmJir aouble-probe system s. . taole for measJrement in industr'al environments. where quic6 and easy-to-nandle methods are requ'red. Data acquisition and calculation of plasma parameters are cantro led ay a personal computer. An evalLation agorithm 's presented and its properties are brielly dscussed. SJccessful operat'on of !ne system can ae proved :n a var:ery of different plasma configurations, namely 'n raaiolreqJency driven, pulsed direct current ana microwave plasmas. Typical measuements and the conclusions that have been arawn are presentea. Plasma aensit'es were in tne range 108-10'3cm-3. From the ena user's point of v:ew the main appl'cation areas are tro-be-snoot:ng, on-line process control and plasma source characterization auring the aevelopment stages of a plasma plant.