10 Gamma alumina-based trace moisture sensors (2-50ppm) have been fabricated. These sensors were mounted on threaded Teflon holders which can be fitted into transformer oil filtration units for detection of trace moisture present in transformer oil. For laboratory testing these sensors were fitted into a customized stainless-steel box and tested rigorously for 6 months for sensitivity, linearity, reproducibility and stability. HP-make LCR meter and 5N nitrogen were used to dry the sensors. A customized setup was used to vary the moisture concentration in ppm level (from 2- 50ppm) and a SHAW (UK)- make dew point meter was used as the secondary reference against which the sensors were calibrated.