Since the discovery of extracellular electron transfer three decades ago, considerable advances have been made in our understanding of this process. Almost as a serendipity, extracellular electron transfer is now the key driver of new technology, where whole microorganisms are used to catalyze electrode reactions. Widely known are microbial fuel cells (MFCs) and Microbial Electrolysis Cells (MECs).  MFCs aim at the production of electrical power from organics, as present in e.g. wastewater, while MECs are more targeting the production of value chemicals during organics oxidation, or for bioremediation. Both can be generically called Bioelectrochemical Systems. Recent work has demonstrated that considerable value can be generated by using the technology for product generation. While initially hydrogen was proposed as end-product, higher value products such as caustic soda and hydrogen peroxide can already be produced, leading to technology which is highly competitive both economically and environmentally. More exciting even is the prospect of using the current produced by microorganisms to drive biocatalysis, and thus produce biochemicals and biofuels. In my talk, I want to discuss results obtained with labscale reactors and a pilot plant MEC for caustic soda production. I will address the key requirements to drive the microbial conversion at the anode, and discuss the environmental benefits derived from this technology, relative to existing wastewater treatment options. Finally, I will highlight options for bioproduction at the cathode.