Slurry-phase hydrocracking is the most suitable technology for the conversion of heavy oils/residues. However, with conventional processes, the production of low-quality by-products is unavoidable. The newly developed Eni Slurry Technology (EST) process reaches total conversion of the feedstock to distillates. A nanosized MoS2 catalyst provides hydrogenation activity, while cracking is mainly of thermal origin. An acid catalyst alone, which would enhance the cracking reaction, is rapidly deactivated under the severe process conditions, but the presence of nanosized MoS2 protects the acid catalyst long enough for potential practical applications, thus allowing a more effective exploitation of unconventional oil resources. (C) 2013 Elsevier Inc. All rights reserved.