Aviation security screening has become very important in recent years. It was shown by Schwaninger et al. (2004) that certain image-based factors influence detection when visually inspecting X-ray images of passenger bags. Threat items are more difficult to recognize when placed in close-packed bags (effect of bag complexity), when superimposed by other objects (effect of superposition), and when rotated (effect of viewpoint). The X-ray object recognition rest (X-ray ORT) was developed to measure the abilities needed to cope with these factors. In this study, we examined the reliability and validity of the X-ray ORT based on a sample of 453 aviation security screeners and 453 novices. Cronbach Alpha and split-half analysis revealed high reliability. Validity was examined using internal, convergent, discriminant and criterion-related validity estimates. The results show that the X-ray ORT is a reliable and valid instrument for measuring visual abilities needed in X-ray screening. This makes the X-ray ORT an interesting tool for competency and pre-employment assessment purposes.