The present paper looks at some aspects of the performance of industrial and environmental thermometers. The aspects of interest here are dynamic response, environmental effects and sensor location. Methods of the response time prediction are briefly discussed. The importance of correct physical properties of fluid and sensor constituents is pointed out. The effects of manufacturing tolerances such as air gaps and porosity of insulants are also discussed. Some attempts at prediction of the sensor performance is heptane and carbon tetrachloride are presented. These predictions are based on water tests and compared with experimental results. Sensor location in a process is not often looked at closely. This is discussed and its importance pointed out.