A new method for the in chamber cleaning of an oil contaminated X- ray detector window in electron microscopes was described. The technique employed reagent grade isopropyl-alcohol or methanol as the detector cleaning agent. Other materials included a polyethylene wash bottle, Teflon tubing, a beaker, carbon paint, a wooden applicator, and clean cloths. A diagram illustrating the assembly of the washer apparatus, and step by step instructions of the cleaning procedure were included. The author concludes that this method is a safe, fast procedure for removing oil contamination from an X-ray detector window without the removal of the specimen chamber.