Sabodala Massawa is the largest gold producing mine in Senegal and one of Endeavour Mining’s cornerstone assets. The Sabodala Massawa gold mine is in the south-east of Senegal, approximately 650 km from Dakar and forms part of the Birimian Greenstone Belt. The mine was recently expanded with the addition of a new 1.2 Mt/a BIOX® production facility to treat high-grade refractory resources. The BIOX® processing facility adds an incremental gold production of 1.35 Moz over the life of the mine. Construction of the USD 290M BIOX® production facility was launched in April 2022 with wet commissioning of the plant commencing in February 2024. First gold from the BIOX® circuit was completed on 28 April 2024 with the plant achieving commercial production on 1 August 2024 (Endeavour Mining, 2024). The BIOX® circuit consists of one backup reactor and six BIOX® reactors configured as three primary reactors operating in parallel and three secondary reactors operating in series. BIOX® product is washed in a three-stage counter current decantation (CCD) circuit with the resulting BIOX® solution treated in a two-stage neutralisation circuit consisting of six tanks in series. The neutralised product reports to a single water recovery thickener with the overflow solution recycled back to the BIOX® plant as process water. This paper covers the main BIOX® design criteria and highlights some novel design approaches adopted for this project. Successful factors behind the BIOX® inoculum build-up and commissioning activities are discussed, pointing out some key take aways for future projects. The performance of the BIOX® circuit over the first year of commercial operation is reviewed with insights provided on where the performance deviated from the design targets. The main challenges experienced during the first year of operation are discussed concluding with initiatives that are underway to further improve the performance of the BIOX® circuit.