According to several social-cognitive models, social knowledge structures described as hostile scripts or schemas may explain why aggressive individuals are prone to attribute hostile intention to others' ambiguous behaviors, a cognitive bias called hostile attribution bias (HAB). The aggression-related concepts in aggressive individuals' semantic memory would be highly accessible, notably through the activation of hostile concepts in nonhostile social contexts, and such an activation would result in HAB. The aim of the study was to test this hypothesis using the N400 component with EEG measurements to assess objectively, in real time, the violation of hostile expectations following a nonhostile situation. To this end, scenarios with a clear nonhostile context (mismatch condition) vs. without nonhostile context (match condition) followed by a character's ambiguous provocative behavior were presented to readers, and ERPs to critical words that specified the hostile intent behind the behavior were analysed. Twelve aggressive and twelve nonaggressive individuals participated in the study. The presentation of a critical word (hostile intent) that violated nonhostile expectation caused an N400 response among nonaggressive whereas such an N400 effect was absent in aggressive individuals. The results suggest that, in nonaggressive individuals, a nonhostile social context activates nonhostile concepts, whereas in the same context, aggressive individuals activate nonhostile as well as hostile concepts. Numerous research applications of the Hostile Expectancy Violation paradigm in the field of HAB are discussed.