PURPOSE: To analyze the concn. of the moisture in a gaseous specimen on-line with high accuracy, by mounting a gaseous specimen sampler to a Karl Fischer (KF) analyzer.

CONSTITUTION: In the case of a liquid specimen, the specimen enters a quantitative pump 1 at first and a definite amount of the specimen is sent to a titration bottle 2. A KF reagent is injected in the bottle 2 by the reagent pump 5 provided in a KF moisture meter 4 while the specimen is stirred by the stirrer 3 in the bottle 2 to perform titration. In the case of a gaseous specimen, a water-soluble solvent is put in the bottle 2 sealed so as to prevent the leakage of the specimen and brought to an anhydrous state by the KF reagent and the gaseous specimen is blown in the solvent on-line by a solenoid valve 10 for sampling the gaseous specimen to absorb a component. The moisture in an absorbing solution is titrated by the KF reagent and the gaseous specimen after absorption is allowed to pass through a gas meter 13 and the rotation of the indicator of the meter 13 is read by an optical sensor to measure the amount of the gaseous specimen. By the conversion from the quantity of moisture and that of the gaseous specimen due to the titration of the KF reagent, the concn. of the moisture in the gaseous specimen is measured.