The new generation of photon counting pixelated X-ray detectors like the Medipix2 detector are gaining increasing interest in medical imaging. In contrast to conventional systems which integrate the charge released in the sensor they are able to count single photons. With this imaging detector it is possible to determine the energy of the incoming X-rays which opens up a new field of applications. One application is the detection of contrast agents in medical imaging which was shown for a silicon sensor. However the absorption efficiency of silicon is very low for the X-ray energies used in medical imaging. High-Z materials such as Cadmium Telluride (CdTe) are therefore promising candidates for the sensor material. With the hybrid design of the Medipix2 detector we are able to realize a photon counting pixelated X-ray detector with CdTe sensor.Crucial for material reconstruction are the energy response functions. With our simulation tool RoSi we are able to simulate these response functions.In this work first results and simulations concerning material reconstruction with a Medipix2 detector with CdTe sensor are shown.