In our previous work, we showed that the structural recovery responses of an epoxy after relative humidity (RH)-jumps through the glass concentration have similar phenomenology to, but different kinetics from, those obtained by temperature (T)-jumps. In this article, we report results from physical aging experiments of the same epoxy after RH-jumps. The results show that time-RH superposition and time-aging time superposition can be used to describe the viscoelastic responses in RH-jump experiments. The similarities and differences between RH-jump and T-jump conditions are also presented. In addition, the difficulties in modeling the combined effects of temperature and relative humidity changes that result from these differences are discussed. (C) 2004 Wiley Periodicals, Inc.