Abstract: This invention is a humidity testing apparatus comprising a test chamber with external heaters for superheating the steam and preventing condensation in the testing zone. The test chamber is divided into an upper humidity testing section and lower condensate collection and removal section by a horizontal heating plate extending from the back wall to a front edge adjacent to and spaced apart from the front of the test chamber, the heating plate extending from one sidewall to the opposing sidewall of the chamber. Convection currents are introduced into the chamber by the heating plate which is maintained at a temperature above the walls of the chamber. The test chamber has a steam inlet opening in the back wall thereof defining a steam flow path into the upper chamber, and a substantially vertical steam baffle plate extending upward from the heating plate and positioned adjacent to the steam inlet opening in the steam flow path. The bottom wall has a condensate outlet opening in the bottom wall thereof.