Because of the complexity of the electron beam (EB) curing process, current understanding of EB curing of polymer resins and composites is limited. This article describes an investigation of different factors affecting EB curing of epoxy resin such as dose rate, time interval between irradiation doses, moisture, and photoinitiator concentration using a calorimetry technique. Results show that higher dose rate resulted in a higher and faster temperature increment in the uncured resin samples, and thus a higher degree of Cure. In the multiple-step EB irradiation, a shorter time interval between irradiation doses resulted in higher temperature in the resin samples and therefore higher degree of cure. Results indicate that moisture could delay crosslinking reaction in the early stages of the cure reaction, but accelerates it later in the curing process. Given a reasonable percentage of photoinitiator, experiments confirmed that samples with higher photoinitiator concentration reach higher degree of cure under same EB irradiation conditions. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2318-2327, 2009