The use of metal oxide semiconductor sensors for the continuous monitoring of hydrogen-sulfide (7783064) was assessed. The monitors studied included General Monitors Models 2180-G1 and 2180-G3, Rexnord Models 710-R4 and 710-R9, MSA Models 500-M2 and 500-M10, Texas Analytical Control Models 110-T5 and 110-T6, and Bacharach Model 550 (with two sensors). Each monitor was composed of a remote sensor wired to a controller. The General Monitors, Rexnord, and MSA models electronically linearized the output from the sensors either at the sensor or at the controller. The Texas Analytical Controls and Bacharach models did not electronically linearize the sensor output and used nonlinear scales on the controllers. No significant zero drift was recorded for any of the monitors tested over a 6 month period. Linear and two piece response curves defined the General Monitors and Rexnord models respectively for the range of 5 to 100 parts per million (ppm). The MSA, Bacharach, and Texas Analytical models showed more complex response curves, but responded to hydrogen-sulfide levels lower than 5ppm. The 75 percent concentration response times for the monitors varied from 10 seconds for the Rexnord models to 152 seconds for the Texas Analytical models, and the fall times varied from 15 seconds for the Rexnord models to 200 seconds for the Texas Analytical models. According to the authors, any of the monitors tested could be used for alarm purposes, due to good zero stability; some of the monitors could potentially give concentration measurements, with some improvements.