A magnetically insulated diode with a cryogenically refrigerated anode is proposed and a prototype of such a diode is constructed. H2O ice is produced on an anode which is cooled with liquid nitrogen. A small machine, consisting of a marx generator and a blumlein line, is used to extract ion beams from the diode. Proton beams of about 50 A and 70 keV are obtained with good reproducibility. Diode electrical characteristics and the extracted beam performance are also examined.