Three types of moisture monitors: MCM Model Dewliixe-20, Panametrics Model System One, and Shaw Model SHA-TRS were tested for accuracy and speed of response over low (10-50 ppm HjO), medium (100-500 ppm HjO), and high (500-4,000 ppm HjO) concentration ranges. The results for the three instruments tested (one of each kind) showed that the MCM instnmient was generally more accurate and responded more quickly than the other two instnmients, with the Panametrics instrument being less accurate (except at low concentration) and slower to respond, and the Shaw instrument was the least accurate and least responsive of the three instnunents during the tests made.