The significant contribution of microbial corrosion to material degradation in industrial environments has been widely investigated, especially in recent years. However, the process remains largely underestimated and, more than ever today, its control is proved to be difficult. Indeed, some recent environmental issues and regulatory led to the reduction of the biocides and anticorrosive treatments, often without an appropriate revision of procedures and without a careful monitoring, thus affecting the effectiveness of the treatments. A multitude of bacterial species lives within the "corrosive" biofilm, where organisms interacts in synergistically or competitive way adapting themselves to external agents, even in extreme conditions. Combining modern electrochemical techniques and molecular biology it is possible today to monitor the biocorrosion risk and to highlight the complexity of the phenomenon. The relevant involvement of specific bacterial strains, including the sulphate reducers and other bacteria of the sulfur cycle, as well as the role of enzymes of the oxidative metabolism has been confirmed by these techniques. These enzymes can be expressed by a vast number of microorganisms, both aerobic and anaerobic, as function of environmental conditions.