H-Oil is an efficient ebullated-bed process for upgrading atmospheric and vacuum residues. Originally developed by HRI, now part of Axens NA, H-Oil is an ideal complement to Axens' fixed-bed Hyvahl process. H-Oil is the preferred choice for processing moderate to high metal residues and/or when a maximum conversion is the objective.

Three specific advanced generation H-Oil processes are marketed:

 - H-Oil-HCC. This heavy crude conversion process produces syncrude. The objective of the unit is to enable just enough conversion to reduce viscosity and increase stability so that the product can be readily transported to an upgrading center.

-  H-Oil-DC. Difficult to treat VGOs and VGO mixtures are processed in this unit with the objective of moderate con-version. Previously known as the T-Star process, this unit is a lighter version of the residue conversion process.

- H-Oil-RC. The classical H-Oil process has been significantly upgraded to increase conversion levels, increase product stability and reduce costs. Among the improvements made to the traditional technology are the integration of IS2 (inter-stage separator) between reactors in series and the application of C2U (cascade catalyst utilization).

Cumulating H-Oil-HCC and H-Oil-RC references, there are currently seven units running around the world.