Three types of moisture monitors: MCM Model Dewluxe-20, Panametrics Model System One, and Shaw Model SHA-TRS were tested for accuracy and speed of response over low (10–50 ppm H2O), medium (100–500 ppm H2O), and high (500–4,000 ppm H2O) concentration ranges. The results for the three instruments tested (one of each kind) showed that the MCM instrument was generally more accurate and responded more quickly than the other two instruments, 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 instruments during the tests made.