Abstract: A method of determining an analyte in an organic or microaqueous solution involves the use of an enzyme electrode at which an enzyme is retained. The enzyme may be immobilised covalently at the electrode but is preferably retained at a hydrophilic support (4) which may be connected to an electrical conductor. Electrochemical detection of analytes in organic or microaqueous solvents using an enzyme electrode has several advantages over existing methods which employ aqueous solutions of analyte. For example compounds with low water solubilities may be detected, detection of a particular analyte may be made more selective by appropriate choice of solvent, the thermal stability of the enzyme may be enhanced and the enzymes may be readily retained at the electrode by virtue of their insolubility in the organic or microaqueous solvent.