PurposeA majority of higher education institutions (HEIs) in Oman, and internationally, have adopted English as the language of education, driven by its power and its globally accepted status as the language of knowledge and communication. Such an internationalisation policy has been inadequately evaluated to examine its actual effects. This paper aims at analysing the existing literature with a view to hypothesise the effects of adopting English as a medium of instruction (EMI) on establishing intellectual capital in the Omani context.Design/methodology/approachThe paper employs a case study design that draws on data generated through a systematic review of 94 peer-reviewed papers that are synthesised using thematic analysis.FindingsThe findings indicate that EMI negatively affects the optimal creation of intellectual capital through limiting access to HE, hindering knowledge transfer, impeding Omanis' employability and hindering faculty's professional growth. EMI leads HEIs to mirror the supplying countries' cultures in terms of materials, ideologies and standards. It affects teaching and research quality, training and communication, the sense of equity, belonging and self-worth amongst students and the relationships amongst faculty members. It also increases reliance on external stakeholders.Research limitations/implicationsThe paper highlights the interconnection between the forms of intellectual capital and how some components are antecedents to the creation of the intellectual capital forms. It establishes the moderating role the language of instruction plays in relation to the three sub forms of intellectual capital in higher education.Practical implicationsThe paper calls for maximising higher education intellectual capital through adopting bilingual rather than monolingual higher education. It calls upon policymakers to revisit the assumptions underlying higher education systems in order to optimise their outcomes.Originality/valueThe paper is the first one that sheds light on the role of language in intellectual capital construction. Such a moderating role has received almost no attention in the higher education literature that is largely busy quantifying its outcomes rather than ensuring they are actually sustainably generated.