A number of new sugar oxidising redox enzymes and variants thereof, viz. pyranose dehydrogenase (PDH), pyranose oxidase (P2O), and cellobiose dehydrogenase (CDH) have recently been electrochemically characterised for use in biosensors for sugar or catecholamine detection but lately also for possible use in biofuel cell anodes. These redox enzymes come from different basideomycete or ascomycete fungi and contain strongly bound FAD in the active site. CDH additionally also contains a cytochrome b. Electron transfer between these enzymes and electrodes can easily be obtained through different mediated approaches using 2 e- H+ acceptors (e.g. soluble quinines) or 1 e-acceptors (e.g., Os2+/3+-complex containing flexible polymers). Additionally due to its cytochrome b domain CDH shows very facile direct electron transfer characteristics with electrodes making third generation biosensors possible. CDHsimilarly to glucose oxidase oxidises the sugar on the C1 carbon making it anomeric sensitive and is selective for the ß-form. Depending on the origin basideomycete CDH is selective for lactose and cellodextrins, whereas ascomycete CDH also efficiently oxidises both monosaccharides and other disaccharides. In contrast PDH and P2O oxidise the sugar on the C2 or C3 carbon (or on both) making them anomeric insensitive. Both PDH and P2O are highly unselective and PDH even oxidises sucrose with a high turn over rate. Additionally especially for PDH there is a possibility that the oxidation product is in turn also a substrate and for some PDHs a sugar molecule can be oxidised up to three times and is thus a very valuable redox enzyme for biofuel cell studies. These enzymes can also be used for amplified detection of catecholamines and similar compounds. At the enzyme modified electrode a catecholamine is initially oxidised into its quinone counterpart and is thus transformed into an active form that can work as a mediator between the reduced enzyme active site and the electrode. Thus an amplification cycle is formed and detection limits in the subpicomolar range can be obtained.