Microprocessor controls maintain humidity and temperature in approximate ranges of and 35°C-70°C respectively. An extra large water jacket minimizes condensation inside the chamber and supports optimum uniformity conditions. A low-pressure water vapor generator controls the humidity in the chamber by injecting saturated water vapor into the recirculating air duct. This process is preferable to steam generation because steam introduces additional heat to the chamber atmosphere, which compromises temperature control. Humidity Test Chambers provide a controlled environment for a wide range of industrial, biotechnical and research related applications.