The aim of the research is to investigate factors that optimize Overall Equipment Effectiveness (OEE) of an underground Bord and Pillar coal mine that has limited coal reserves and unfavourable geological conditions. The mine consists 10 CM sections, mining both high and low seams with equipment-suits that comprises the Continuous Miner (CM), Shuttle Cars, Feeder Breaker, Conveyor Belts and Roof Bolter. Three elements making up the OEE equation (Availability, Performance Rate, Quality), are reviewed to establish factors that influence OEE improvement. The research paper employs deductive, quantitative research methods, analyzing 18 months performance data. The main source of data is the mine’s Enterprise Resource Planning (ERP) system.  Average OEE figures are 45%. Quality and productivity rate figures are 85% and 103%. Availability figures average 52% and presents opportunity for OEE improvement. Geological conditions inherently contain mining inefficiencies leading to losses of direct operating hours (DOH), which affects the availability component of OEE. OEE improvement results are obtained through analysis of CM sections that have shown a positive shift in OEE performance. The results demonstrate that DOH improvement leads to optimized equipment uptime, thereby increasing availability. DOH improvement is achieved through effective operational downtimes management and good equipment maintenance management practices.