Beside Wolter I X-ray optics, which are used at most in currently operating X-ray space telescopes, there exist also other optical designs and their usability for space observations is still the matter of studies. This presentation covers preliminary testing results of an optical module which is based on a modified Kirkpatrick- Baez optics. This X-ray optics, consisting of four sub-modules, was assembled in Prague and tested at the PANTER test facility of MPE afterward. The sub-modules use different reflective coatings, in part developed by our research group, on complementary flat mirrors, which approximate the shape of a Kirkpatrick-Baez optical design. In this presentation, I summarise the design of the optical modules, the details of applied coating layers, and the X-ray characterisation results at the PANTER test facility.