This study presents an assessment and long-term forecast of corrosion processes in the flooded "Centralna" coal mine, located in Myrnohrad, Donetsk region, Ukraine. This mine is currently in the zone of active military operations. Coal mining has stopped and mining equipment is subject to uncontrolled flooding by groundwater. This flooding has resulted in significant hydrogeological and geochemical changes within the underground workings and adjacent aquifers. The research focused on evaluating the chemical composition of groundwater and its influence on the corrosion of metallic equipment flooded in the mine. Laboratory analyses of groundwater were conducted on 130 parameters, with key indicators including pH (7.7), electrical conductivity (3610 μS/cm), chlorides (267 mg/l), and sulfates (1030 mg/l). The composition of metal structures, including structural, carbon, alloy and high-strength steels, was studied. The total mass of the flooded metal equipment in the mining and development sections is approximately 3,300 tons. Despite the slightly alkaline pH, elevated concentrations of chlorides and sulfates, combined with high water conductivity, were found to significantly increase the corrosion potential of mine water. Expert assessments using an integral scoring system identified chlorides as the dominant corrosion factor (16.2 points out of 20), followed by conductivity (13.2) and sulfates (12.5). A predictive model was developed to estimate long-term corrosion rates and the corresponding increase in ferrous iron (Fe²⁺) concentrations in the groundwater. Three corrosion rate scenarios (0.05, 0.1, and 0.15 mm/year) were examined over a 30-year period. Results indicated a gradual acidification of mine water, with pH decreasing to 6.67 and Fe²⁺ concentrations potentially reaching 325 mg/l. These processes are consistent with patterns observed in other flooded coal mines in Eastern Europe. The findings emphasize the importance of long-term monitoring of hydrochemical conditions in flooded mining environments to predict potential ecological risks associated with groundwater contamination by metals.