A new system of dew point temperature hygrometer, based on semiconductor MEMS detector is presented in the paper. Many details of MEMS detector construction are given with details in the report. Basic idea of algorithms of detector control is also discussed. More attention is devoted to subalgorithm for self-adjusted detector threshold operation. Excellent dynamic parameters of the new hygrometer (i.e. 2÷5 dew point detections and temperature measurements per second), proved by the hygrometer tests, will be presented and described in the report. It means that presented hygrometer is 10÷100 times faster than conventional hygrometers. In the end of the paper two medical applications are demonstrated with clinical test results. The first application is for dermatology for TransEpidermal Water Loss (TEWL) factor of human skin. The second is focused on measurement of humidity in human nose cavity and human throat during breathing. In both case fast humidity measurements, with time constant of some 0.5s, have been required. Copyright © 2008 by ASME.