This paper details the processing steps used to fabricate front and back side processed, unintentionally doped bulk GaAs Schottky detectors and presents the results of current-voltage (I-V) and X-ray characterization of the detectors. GaAs detectors with large enough thickness and low enough doping could be used for X-ray imaging, especially for medical applications. For this experiment, we fabricated GaAs Schottky wafers using front and back side photolithographic processing with Ti/Au for the Schottky contacts and Ge/Au/Ni/Au for the ohmic contacts. We then tested a number of 2 mm(2) detectors. The breakdown voltage reached 600-800 V reverse bias in these GaAs Schottky detectors and the dark current was found to be between 2 and 90 nA. These detectors were also characterized using 150 keV, 3 mA X-ray radiation and the response indicated more than a hundredfold increase in photocurrent. These detectors with their high breakdown voltage will enhance the charge collection efficiency. In addition, thicker samples with high breakdown voltage can be used. which will provide even higher stopping power, thus making these detectors suitable for high energy X-ray detection. Published by Elsevier Ltd.