The current study evaluates pre-combustion microbial desulphurization of medium – sulphur type coal containing total sulphur (1.45 wt. %) and pyritic sulphur (≥ 0.51 wt. %) in a laboratory scale. Coal samples used in the current study were supplied by one of South African Power Utility, Eskom power station as received from the nearby Waterberg coalfield in Limpopo in South Africa... After a stipulated hydraulic retention time (HRT), the coal samples were filtered, washed, dried and analyzed for total sulphur, ash content and calorific values. The calorific value of the coal significantly improved from 20.42 MJ/Kg to 24.16 MJ/Kg on the 5th day. The process removed up to 72 % of the total sulphur content in the coal samples at an HRT of day 9th. Furthermore, ash content reduced by 16 %. This study provides a novel breakthrough of an alternative microbial desulphurization process of Waterberg steam coal as a pre-treatment technique in order to meet stringent environmental emissions standards for SO2.