The intent of this paper is to review the different sensor technologies that are in use today for the measurement of water vapor content in natural gas. It will also address key issues and proper procedures in assembling a sample delivery system to provide a clean, representative gas sample to the sensing device. Natural gas is one of the most widely used fuels today for everything from home heating to power generation, and maintaining the gas quality is of great concern. The determination of the water vapor content in natural gas is one of several key factors used to determine the ultimate quality of the gas. With economic conditions as they exist today, many companies have been forced to cut personnel in order to maintain a reasonable balance sheet. The loss of experienced measurement technicians places a heavy burden on instrument manufacturers to provide an accurate and reliable means of making this measurement