Homoepitaxial diamond Schottky diodes with leakage current less than 10(-7) A cm(-2) up to the breakdown voltage of 90 V are discussed. Under forward voltage an exponential current increase over six orders of magnitude and an ideality factor of n<1.2 is observed. At elevated temperature, thermally activated reverse leakage currents are present as commonly observed, however breakdown is not degraded. The experiments allow to discuss design rules for high-voltage diamond Schottky diodes. (C) 1997 Elsevier Science S.A.