Equipment and procedures for the rapid measurement of the water vapor permeability of polymer films and food coatings has been evaluated. The method uses an electronic sensor to measure the concentration increase in water vapor diffusing through a film into a chamber of known volume. Air of known humidity is passed over each side of the film to establish a desired equilibrium relative humidity differential prior to each test. Experimental results showed that moisture vapor transmission rates of polymer packaging films and edible coatings could be determined in a range from 0.25 to 12 hours instead of the usual 24 hour period required by existing tests. Permeance values for Teflon, high density polyethylene (HDPE), polyethylene terephtalate (PET) and three coating materials were measured at relative humidity differentials between 0 - 100% and temperatures between 5 and 30°C. Results were found to be similar to values reported in the literature using standard measurement methods. This method allows the measurement of film and coating permeance values at temperature and relative humidity values close to actual food storage conditions. / Graduation date: 1994