The objectives of this study are to determine the influence of low-density polyethylene (LDPE) on the structure and morphology of the resulting semicoke as an intermediate carbon material in metallurgical coke manufacture; and, to explain the differences in the fluidity and the coking pressure generated during the carbonization process.The Spanish Ministry of Education and Science (Ministerio de Educación y Ciencia), Project CTM2004-03254. El Principado de Asturias, "Plan de Investigación, Desarrollo Tecnológico e Innovación de Asturias”.Peer reviewed