A Hard Science Spoken Word List (HSWL) was developed and validated to help second language learners of hard sciences better comprehend academic speech at English-medium universities. It consists of the 1,595 most frequent and wide ranging word families in a 6.5-million running word hard science spoken corpus which represents 12 subjects across two equally-sized sub-corpora. Its coverage in different discourse types indicates that the HSWL truly reflects the language in hard science academic speech. The comparison between the HSWL with Dang, Coxhead, and Webb’s (2017) Academic Spoken Word List shows that the HSWL focuses more on specialized vocabulary in hard science speech. Depending on their vocabulary levels, learners may achieve 93%–96% coverage of hard science academic speech with knowledge of the HSWL words. Keywords: hard sciences, academic spoken discourse, corpus, word lists, vocabulary Published online: 16 April 2018