The ethylene permeability of a wheat gluten filmwas studied as a function of relative humidity (RH) (from 0 to 100%) and temperature (from 3 to 45◦C), using response–surface methodology. Ethylene permeability values ranged in a wide scale from 1 to 3098 amolm−1 s−1 Pa−1. The exponential effect of relative humidity on ethylene p ermeability was related to the boosting effect of increasing film water content on ethylene solubility and diffusivity in the hydrated film. The temperature dependency of the ethylene permeability data showed a strong disruption near the glass transition temperature value (25 ◦C at 75% RH). The glass transition phenomenon and its effect on chain mobility could explain the interesting synergic effect of both temperature and relative humidity on ethylene permeability of wheat gluten film.