Abstract: The subject of this research is the semantics of English and Russian lexemes that represent the conceptual component of the concept of mercy in both languages. The goal of this work consists in determination of similarities and differences of the conceptual attributes of mercy in the English and Russian legal texts of the XVII – XVIII centuries. The concept of mercy was selected due to insufficient examination of its verbalization in the comparative linguistics. In the course of this research, the author applied comparative method, semantic analysis, quantitative method, and method of modeling, Based on the legal texts of Great Britain and Russia of the XVII – XVIII centuries, the author determines the composition of core lexemes and their synonyms, which are capable of resembling the conceptual characteristics of mercy in the compared languages. The scientific novelty consists in the establishment of similarity and difference of the conceptual characteristics of mercy in the Russian and English legal texts of a certain period of time. As a result of the conducted analysis, it was revealed that in the English texts of that time, the notional component of the concept represents the core lexemes and synonyms “grace”, “mercy”, “reprieve”, “forgiveness”, “indulgence” that are the synonyms of core lexemes, while in the Russian texts this is the core lexeme “mercy”, and its synonyms “grace”, “clemency”, “remission” and “forgiveness”. Comparison of composition of the conceptual attributes of mercy in the English and Russian legal texts of the XVII – XVIII centuries illustrated that they had more differences. Thus, the conceptual attributes of mercy in the English text, understanding of forgiveness as an act of mercy, grace, or manifestation of reprieve from a king or queen; or mercy as an abolition of punishment, benevolence of God, act of leniency and forgiveness for an offence. The conclusion is also made on similarity of the compared languages in perception of mercy as an act of grace from the ruler of the country.