The study deals with emphatic constructions in English and Arabic scientific texts. To the researcher's best knowledge, this topic received little attention from linguistic researchers, exceptionally in functional grammar analysis. The importance of this study arises from the fact that some syntactic forms are effective linguistic choices for conveying the meaning of emphasis to the readers. The study aims to identify and analyze different types of linguistic constructions in English and Arabic scientific texts and show the similarities and differences between the two types of scientific texts under investigation. The study intends to analyze the structure of complex clauses by adopting Halliday and Matthiessen's (2004) modal of 'Systemic Functional Grammar' of syntax and Prince's (1978) modal of 'Given-New' information of discourse analysis. These models analyze-samples of English 'Spaceport' magazine and pieces of Arabic 'Sadeem Bulletin' magazine. Moreover, the study depends on a qualitative approach to answer the research questions and confirm its hypothesis. The results show that both languages use some syntactic forms, but Arabic is rich in its constructions. This difference is due to the nature and flexibility of both languages. The findings will be helpful for researchers concerned with syntax and scientific issues because it provides a rigorous analysis of complex clauses into simple parts and shows the focus of information in its suitable.