Emmanuïl Bogdanovych Chekaliuk (Ukrainian: Емануїл Богданович Чекалюк Gnizdychev, Zhydachiv District, Lviv Oblast, May 6, 1909 – Lviv, January 5, 1990) was a Ukrainian petroleum engineer and statistical thermodynamicist. He first produced rigorous physical and mathematical evidences of petroleum thermodynamic stability at mantlean conditions. Since the 1990s the heavy hydrocarbons mixture enriched with organometallic compounds is widely known as "Chekaliuk’s petroleum".