[en] This paper reports on a number of very sour gas dolomitic reservoirs suspected of having large amounts of sulphur. This sulphur shows up on the form of inclusions in cores and thin-sections. There is no laboratory method currently available for the determination of the total sulphur in the reservoir rock. Solvent extraction was used for partial removal of the sulphur from two pieces of core. A preliminary project established the value of X-ray Computer Assisted Tomography (CAT) Scanning in determining residual sulphur after extraction. A procedure was established and used for the determination of the sulphur content in a number of core pieces of a target reservoir. The sulphur saturation was calculated using a computer model developed in-house. It is the first time such an approach has been attempted. The results showed a wide saturation range of the sulphur present in the core. The average sulphur saturation of eight core peices has been estimated at 34.1%. The core porosity was corrected to consider the volume occupied by the sulphur as part of the fluid volume